According to the section header, this chapter is the response to five men with an "earnest desire" to know their duties in the church. Joseph produced this revelation glittering with gems of divine wisdom as a result. The duties are as follows:
Oliver: preach to the church and to the worldHyrum: exhort and strengthen the churchSamuel: exhort and strengthen the church, but don't preach to the worldJoseph Sr: exhort and strengthen the churchJoseph Knight: pray vocally in all places, and also exhort the church
I have a feeling these men were hoping for more detailed, more personalized revelations. All of them are supposed to preach to the church. Samuel is the only one specifically prohibited from preaching to the world. Joseph Knight is told to take up his cross and pray, but also to do the same things the others were told to do.
The church is in its infancy and its eager new leaders are looking for direction on what they need to be doing because the work is so exciting and they want to be involved. But they're merely told to preach and to help out in disappointingly non-specific terms. And that's about it. There isn't anything particularly groundbreaking for them in here, since I'm sure they already knew that missionary work and strengthening the church were important.
Bafflingly, God, in his infinite wisdom (or, more accurately, in Joseph's limited imagination), chooses to reward these men's enthusiasm by giving them what amounts to somewhere between a form letter and a bad tarot reading.