"And it came to pass that he built an altar of stones, and made an offering unto the Lord, and gave thanks unto the Lord our God."
The alter was to be made out of whole stones which no iron tool was to touch. By the cutting of the stone by iron it was considered polluted or dirty.(Exodus 20:25, Deut. 27:5, & Josh 8:31) Why? Iron symbolizes here evil, because of the connection with Tubalcain, and instructor of iron who revealed dark dealings of Satan. (Moses 5:46,49)
The alter is a place of both thanksgiving and of prayers for help. The sacrifice, usually a goat or a lamb was to show a way of what is now known as tithing. By willingly giving a portion of what one owned the Lord could and would bless one with the so many blessings that there would not be room big enough to accept it all. (Malachi 10)
The first thing Lehi did after they pitched their tents was to give thanks to the Lord. After doing so much for them Lehi recognized the Lord deserved the credit and the praise. After all, the Lord saved Lehi from the angry people of Jerusalem and protected his family. What a great blessing, one well deserving the praise and gratitude of a faithful servant.