When a new dispensation of the gospel is being introduced the Lord inspires his servants to follow a procedure which is acceptable to the Lord. In this case Alma baptized himself at the same time he baptized Helam. Thereafter, according to verse 15 he baptized each individual without being immersed himself. A portrayal of Alma baptizing at the waters of Mormon will be found in volume two of Treasures from the Book of Mormon on page 108.