Moroni tells the Lamanites about how the Nephites baptized people.
First the elders, priests, and teachers were baptized, and then everyone else after proving themselves worthy.
4 And after they had been received unto baptism, and were wrought upon and cleansed by the power of the Holy Ghost, they were numbered among the people of the church of Christ; and their names were taken, that they might be remembered and nourished by the good word of God, to keep them in the right way, to keep them continually watchful unto prayer, relying alone upon the merits of Christ, who was the author and the finisher of their faith.
The newly-baptized people then were cleaned with the Holy Ghost, and put on the church directory.
The church had regular meetings to fast, pray, tell each other about how their souls were doing, to eat bread, drink wine, and remember Jesus. 
7 And they were strict to observe that there should be no iniquity among them; and whoso was found to commit iniquity, and three witnesses of the church did condemn them before the elders, and if they repented not, and confessed not, their names were blotted out, and they were not numbered among the people of Christ.
Church members who did something wrong were publicly condemned and excommunicated, if three members of the church testified against them.
9 And their meetings were conducted by the church after the manner of the workings of the Spirit, and by the power of the Holy Ghost; for as the power of the Holy Ghost led them whether to preach, or to exhort, or to pray, or to supplicate, or to sing, even so it was done.
The meetings were run by the Holy Ghost.
They preached, prayed, or sang whenever and however the Holy Ghost told them to.