Alma Chapter 6
Alma 6:6 Alma commanded the people that they should join in fasting and mighty prayer in behalf of the welfare of the souls of those who knew not God.
1 And now it came to pass that after Alma had made an end of speaking unto the people of the church, which was established in the city of Zarahemla, he ordained priests and elders, by laying on his hands according to the order of God, to preside and watch over the church.
verse 1 "he ordained priests and elders" While it is clear that Alma ordained brethren to help lead the church, it is not clear that "priests" and "elders" were specific offices in the priesthood as we know them today. We do know that the Aaronic priesthood was not to be found among them (Joseph Fielding Smith, Doctrines of Salvation 3:87), thus the office of "priest" in Alma's day was likely more akin to what we would term "high priest" today. These were priests of the higher or Melchizedek priesthood.
"The order of God" is the priesthood. Note that Alma ordained these men "by laying on his hands."
2 And it came to pass that whosoever did not belong to the church who repented of their sins were baptized unto repentance, and were received into the church.
3 And it also came to pass that whosoever did belong to the church that did not repent of their wickedness and humble themselves before God-I mean those who were lifted up in the pride of their hearts-the same were rejected, and their names were blotted out, that their names were not numbered among those of the righteous.
verse 3 "the same were rejected, and their names were blotted out" Reference is made here to the practice of excommunication.
4 And thus they began to establish the order of the church in the city of Zarahemla.
verse 4 The "order of the church" refers to the authorized structure and procedures according to the priesthood.
5 Now I would that ye should understand that the word of God was liberal unto all, that none were deprived of the privilege of assembling themselves together to hear the word of God.
verse 5 Here is a reminder that no sincere person, regardless of their social standing or any other categorization, is to be turned away from the congregations of the church.
6 Nevertheless the children of God were commanded that they should gather themselves together oft, and join in fasting and mighty prayer in behalf of the welfare of the souls of those who knew not God.
verse 6 "Oft" means often. The "children of God" here are members of the church. They are commanded to do some missionary work.
7 And now it came to pass that when Alma had made these regulations he departed from them, yea, from the church which was in the city of Zarahemla, and went over upon the east of the river Sidon, into the valley of Gideon, there having been a city built, which was called the city of Gideon, which was in the valley that was called Gideon, being called after the man who was slain by the hand of Nehor with the sword.
verse 7 For a model of the possible relationships between the city of Zarahemla, the River Sidon, and the valley of Gideon, see the Hypothetical Map of Book of Mormon Lands.
8 And Alma went and began to declare the word of God unto the church which was established in the valley of Gideon, according to the revelation of the truth of the word which had been spoken by his fathers, and according to the spirit of prophecy which was in him, according to the testimony of Jesus Christ, the Son of God, who should come to redeem his people from their sins, and the holy order by which he was called. And thus it is written. Amen.
verse 8 Again, "the holy order by which he was called" refers to Alma's priesthood.