Declare these things

What is the mission of the Lords servants? What is their responsibility? The appearance of 3 Nephi 12 the Lord tells the people what to do after they had seen Him.

1 blessed are ye if ye shall believe in me and be baptized, after that ye have seen me and know that I am.
2 And again, more blessed are they who shall believe in your words because that ye shall TESTIFY that YE HAVE SEEN ME, and that ye know that I am. Yea, blessed are they who shall believe in yourwords, and come down into the depths of humility and be baptized, for they shall be visited with fire and with the Holy Ghost, and shall receive a remission of their sins. (3 Nephi 12:1-2)

Blessed are those that believe in THESE people who have seen, when they shall testify that they have seen Him. We shouldn't discount others experiences because they come from unknown sources. More on this later.

That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked at and our hands have touched…WE PROCLAIM to you what we have SEEN and heard” (1 John 1:1,3)

In the Joseph smith Papers a discourse to the early apostles by Oliver Cowdery is given. Go ahead, read the entire discourse its a great talk.

We have work to do, that no other man can do. You must proclaim the Gospel in its simplicity and purity. and we commend you to God and the word of his grace. You have our best wishes, you have our most fervent prayers, that YOU MAY BE ABLE TO BEAR THIS TESTIMONY, THAT YOU HAVE SEEN THE FACE OF GOD. Therefore, call upon him in faith and mighty prayer, till you prevail, for it your DUTY and your privelege to bear such testimony for yourselves. We now exhort you to be FAITHFUL TO YOUR CALLING, there must be no lack here. You must fulfil in all things, and permit is us to repeat, all nations have a claim on you. You are bound together as the three wit nesses were. You, notwithstanding can part & meet & meet and part again till your heads are silvered o[v]er with age. (Joseph Smith Papers, Minute Book 1, 12 Feb. 1834, 27–29., here)

They are supposed to bear testimony if they have it. But first they must receive it. It is their duty. By not doing so you are not magnifying your calling if you have it (unless commanded differently). And if you don’t you must gain it to magnify their calling. Joseph smith also called 12 apostles who had not received this testimony yet. Though they were allowed to not have it and still be called to the 12, they were meant to receive it however and testify of it when they did. But as Oliver Cowdery later stated the apostles ordinations are not complete until God has laid His hands on their head.

The people were asked earlier in the discourse "Tarry at Kirtland until you are endowed with power from on high.". Some believe they are called to this work by descent of man. But as I have shown in many posts now, (my most recent Priesthood Revisited) its not by "descent of man" (Joseph Smith) but by Gods voice (JST Gen 14), or as Oliver described "Your ordination is not full and complete till God has laid His hand upon you.". Finally the discourse ends with

"You have our best wishes, you have our most fervent prayers, that you may be able to bear this testimony, that you have seen the face of God. Therefore call upon Him in faith in mighty prayer till you prevail, for it is your duty and your privilege to bear such testimony for yourselves." (ibid)

While the discourse was directed to the newly called apostles, it applies to all the disciples of Christ, those who wish to be His servants.

Other Declarations

11: behold, the angel of the Lord appeared unto them; and he descended as it were in a cloud... 

32 And now it came to pass that Alma began from this time forward to teach the people, and those who were with Alma at the time the angel appeared unto them, traveling round about through all the land, publishing to all the people the things which they had heard and seen, and preaching the word of God in much tribulation, being greatly persecuted by those who were unbelievers, being smitten by many of them. 

48 And now, when they heard this they cast up their eyes as if to behold from whence the voice came; and behold, they saw the heavens open; and angels came down out of heaven and ministered unto them. 49 And there were about three hundred souls who saw and heard these things; and they were bidden to go forth and marvel not, neither should they doubt. 50 And it came to pass that they did go forth, and did minister unto the people, declaring throughout all the regions round about all the things which they had heard and seen, insomuch that the more part of the Lamanites were convinced of them, because of the greatness of the evidences which they had received. (Helamen 5) 

The first thing they do after having this great experience is to go bring others unto repentance and testify unto them the things they had both heard and seen. They had seen angels! They had the windows of heaven (notice what the windows of heaven are, nothing to do with money or temporal things) opened unto them due to their faith and baptism by fire which they had just received earlier in the chapter. Here we have again the Lords servants testifying to the people, the people are converted to the Lord and experience the things of heaven. Than they go out and gather others.

That is the purpose of these events. Moroni 7 explains that the purpose of these great experiences (angels, gifts of the spirit, manifestations of the spirit) is to increase faith in the land. That we may all be profited together, not to be hidden under a bushel (D&C 46:26,29). Until we (those with little faith) may lay hold upon the same blessings and call upon the powers of heaven for themselves. As the lectures on Faith, it requires one to believe on the testimony of others until we can gain the same testimony for ourselves.

We have Nephi, Jacob, and Isaiah (from the Bible) who saw Him (2 Nephi 11:1-2).

Jacob when confronting the AntiChrist Sherem could not be shaken due to his many revelations he had and we learn when one is fully converted they "never did fall away" (Alma 23:6),

5 And he had hope to shake me from the faith, notwithstanding the many revelations and the many things which I had seen concerning these things; for I truly had seen angels, and they had ministered unto me. And also, I had heard the voice of the Lord speaking unto me in very word, from time to time; wherefore, I could not be shaken. (Jacob 7:5)

1) Revelations
2) Seen Angles
3) Had Angels Minister to Him
4) Heard the Voice of the Lord

Notice the voice of the Lord is different than the voice of the Holy Ghost. Seems to follow the endowment very well. First we receive the Holy Ghost. Than it shows us what we should through revelation. Than true messengers minister. We continue faithful, we will "hear" God's voice. As we continue faithful to the commandments of God the time will come where we can converse with the Lord through the veil and enter therein.

Ressurection of Christ
Many examples of others testifying of Christ's Resurrection in the Bible can be found here.
http://www3.telus.net/trbrooks/12groups.htm

Who was the first witness of His ressurection as the Second Comforter? Who was the second? Third? Who cares right?

9 ¶Now when Jesus was risen early the first day of the week, he appeared first to Mary Magdalene, out of whom he had cast seven devils.
10 And she went and told them that had been with him, as they mourned and wept.
11 And they, when they had heard that he was alive, and had been seen of her, believed not.
12 ¶After that he appeared in another form unto two of them, as they walked, and went into the country.
13 And they [The two] went and told it unto the residue: neither believed they them.
14 ¶Afterward he appeared unto the eleven as they sat at meat, and upbraided them with their unbelief and hardness of heart, because they believed not them which had seen him after he was risen (Mark 16.9-14)

First Mary Magdalene, who told others yet they believed her not.

Second there were two. Luke 24 tells us one of these men was Cleopas and the other an unknown disciple. They too did not believe, and the Lord says "25 Then he said unto them, O fools, and slow of heart to believe all that the prophets have spoken" in verse 31 their eyes are opened to His true identity.

Third the eleven are chastised for not believing the witness of the others. These are the 12 apostles (11 were present) to the lamb. The "presidency" of the church. Yet they would not believe the words of others that had seen Him and were chastised for the hardness of heart, and unbelief.

Are we so quick to discount those who testify because they are not a "leader" or because they are not the "15" of the church?  The Lord appeared to many others first and chastised those who did not believe including the "apostles". Also the order of events teaches a great truth about the order of events for ourselves which I won't get into. There are great truths hidden in this sequence of events.

Arise and Come Forth

Arise and come forth unto me, that ye may thrust your hands into my side, and also that ye may feel the prints of the nails in my hands and in my feet, that ye may know that I am the God of Israel, and the God of the whole earth, and have been slain for the sins of the world” (3 Nephi 11:14)

What you Should Do Now 
Receive your Baptism by Fire and the Holy Ghost (different than the gift of the holy ghost by laying on of hands). That you may enter in by the way. Nephi tells us.

1 And now, behold, my beloved brethren, I suppose that ye ponder somewhat in your hearts concerning that which ye should do after ye have entered in by the way. But, behold, why do ye ponder these things in your hearts? 

5 For behold, again I say unto you that if ye will enter in by the way, and receive the Holy Ghost, it will show unto you all things what ye should do. (2 Nephi 32:1, 5)

As Orson Pratt said, (which includes the Sisters)

This failure to realize all the blessings and powers of the Priesthood does not apply to the elders and lesser Priesthood only; but it applies to the higher quorums, and comes home to ourselves, who are Apostles of Jesus Christ. We are presented before the Church, and sustained as prophets, seers and revelators, and we have received oftentimes the gift of prophecy and revelation, and have received many great and glorious gifts. But have we received the fullness of the blessings to which we are entitled? No, we have not. Who, among the Apostles have become seers, and enjoy all the gifts and powers pertaining to that calling? And those who are called to perform special missions in opening up dispensations of the Gospel to the children of men, as Joseph and others were called of the Lord, He endows more fully with these gifts; but this does not hinder others from enjoying similar gifts according to His promises, and according to our faithfulness. And I have thought the reason why we have not enjoyed these gifts more fully is, because we have not sought for them as diligently as we ought. I speak for one, I have not sought as diligently as I might have done. More than forty years have passed away since these promises were made. I have been blessed with some revelations and prophecies, and with dreams of things that have come to pass; but as to seeing things as a seer, and beholding heavenly things in open vision, I have not attained to these things. And who is to blame for this? Not the Lord; not brother Joseph—they are not to blame. And so it is with the promises made to you in your confirmations and endowments, and by the patriarchs, in your patriarchal blessings; we do not live up to our privileges as saints of God and elders of Israel; for though we receive many blessings that are promised to us, we do not receive them in their fullness, because we do not seek for them as diligently and faithfully as we should." (Orson Pratt, JD 25:145-146, http://jod.mrm.org/25/144)