We should read this verse in the context of the last phrase of verse 1:
I would that ye should remember that the Lord God ordained priests, after his holy order, which was after the order of his Son, to teach these things unto the people.
And those priests were ordained after the order of his Son, in a manner that thereby the people might know in what manner to look forward to his Son for redemption. (Alma 13:1–2)
Alma is setting up his appeal to ancient authority. His first point is that when Yahweh established his priests (those endowed with his authority) he did so “after the order of his Son.” This point is important because the Ammonihahites do not recognize this aspect of the Messiah. Not only does Alma claim an ancient authority; but by linking it to the Son (Yahweh-Messiah), he excludes Ammonihah’s lawyers from it. (See “Excursus: The Nephite Understanding of God,” following 1 Nephi 11.)
These priests were ordained in a manner that would teach people to look forward to the mission of the Atoning Messiah. While this phrasing might suggest a form of ordination that was a symbol (or a “type,” in Book of Mormon terms), Alma clarifies that meaning in the next few verses. His narrative of their ordination parallels the concepts he has just finished teaching about the second death. Thus, he will use the priests as his touchstone of authority and, from that touchstone, strengthen the points he has already made.
Translation: “Forward” is used (v. 1) to indicate an event in the past, but here it looks to the future: “to look forward to his Son for redemption.”