What would we say if someone asked how they should "begin to exercise their faith?"
Alma chose three scriptural witnesses to tell them what seed to plant and where their faith should begin. He used two witnesses that are lost to us except for these passages in the Book of Mormon - a beautiful prayer by a prophet named Zenos and a single sentence from a prophet named Zenock. The reason that he used both passages is that they referred to the mercy that is available to us because of the Son of God. His third witness was the story of the children of Israel when their camp was infested with poisonous serpents. Moses fashioned a brass serpent and raised it on a staff in likeness of the eventual sacrifice of the Savior. All who looked up at this image lived.
Alma taught from the scriptures with examples that had meaning to the people he taught. He used the prayer of Zenos not just to teach them that ancient prophets testified of the Son of God, but to connect with their concern that they could not worship because they had been cast out of the churches they had helped build. He had a second witness from an ancient prophet Zenock, and he had a scripture story of Moses with which they should have all been familiar, but the significance of which they clearly did not understand. Teach from the scriptures as there is great power in the word.
This is a masterpiece of teaching. Alma's summary ties these things together beautifully.
22 . . . abegin to believe in the Son of God, that he will come to redeem his people, and that he shall suffer and die to batone for their sins; and that he shall crise again from the dead, which shall bring to pass the dresurrection, that all men shall stand before him, to be ejudged at the last and judgment day, according to their fworks.
23 And now, my brethren, I desire that ye shall aplant this word in your hearts, and as it beginneth to swell even so nourish it by your faith. And behold, it will become a tree, bspringing up in you unto ceverlasting life. And then may God grant unto you that your dburdens may be light, through the joy of his Son. And even all this can ye do if ye ewill. Amen.