[There are 5 general lessons in PMG. The first deals with how God manages His truth and authority on the Earth. He always gives the authority to act in His name to one man, who may be allowed (depending on circumstances) to extend that power to others. Adam, Moses, Alma, Isaiah, Nephi, and others (Enoch, Noah, Samuel, Amos, Jeremiah, Mormon, Moroni, etc--find them yourselves) are examples of single holders of God's authority to act and speak on Earth. The 12 apostles all had authority from God to act--that's why they all taught. This authority from God extends to the people that are near those authorized or whom they can reach. For example, both Micah and Isaiah lived and prophesied around the same time. In fact, we know that they lived at the same time, but were called to different halves of the kingdom. Christ called 12 apostles in Jerusalem, and a different 12 in the Americas.
The role of these individuals is to administer the saving ordinances (see the like the the 12 in the Americas) such as baptism and giving the gift of the Holy Ghost. They also receive revelation for large groups of people, to ensure that people follow the Lord. This authority is lost from time to time, and the Lord must call a new prophet, grant him His authority, and teach him. This is one of the functions Christ played during His mortal ministry, as the Jews at the time had apostatized from the true meaning of the Law (see Hebrews for an explanation). This restoration by God Himself and losing of this authority and corrupting God's truths by man is a cycle that has been repeated many times in the history of our world. In fact, after Christ came, the new church eventually fell into apostasy again (see John's remarks about a church leader who would excommunicate any who tried to listen to the apostles). Revelation begins by threatening 5 of the 7 churches in the Roman providence of Asia (see Revelation 3 and 4). There are other things that show an apostasy happened, as well. But, in modern times, Christ has restored His church and clarified His doctrine!
He has done this through a prophet, named Joseph Smith. This man wanted to find truth, but all the different churches understood things so differently, that he was confused. Finally, after reading James 1:5-6, he decided to pray and see what God had to say. He received a vision because of the sincerity and pure intent of his prayer, and in this vision he was told that there was no church on earth at the time with the authority to act as God's organization for salvation, nor one that had pure doctrine. So, young Joseph was prepared over years, until he was ready for the responsibility of being the instrument in God's hands to restore the fullness of truth.
The Book of Mormon is one of the tools used by the Lord to clarify His doctrines. When used together with the Bible, doctrinal disputes are clarified and nullified, and clarity can reign. The best part of this message? We know for sure why were're here, where we will be going after death, what the purpose of life is, how to successfully navigate through life, and how to receive guidance from the Lord personally. That's actually my favorite part: we don't need to blindly believe anything. We clearly know how God will answer our prayers, and learn to understand the whisper of the Spirit, so that we have a direct, ever strengthening relationship with the Lord.
The rest of the lessons indulge on sub-points of that: what the Lord expects us to do, why He expects that, what we receive, what we must give, and how to farther progress in this life towards God. So, lessons include the Plan of Salvation (God's plan, proposed to and accepted by us before this world even existed which included our coming here to grow), the Gospel of Jesus Christ (what we need to do in this life to prepare to return to our Father in Heaven and to progress to the next stage of our eternal progression), as well as various commandments and laws of the Lord. I will discuss those more as time goes on.
My primary message is to investigate honestly what I claim and have to offer, and then pray to know for yourself. If it is, God will let you know in your mind and in your heart. Try what I will teach--you will feel it's effects, and eventually things in your life will even begin to change. That's a promise that has been given by multiple prophets, by the Lord Himself, and by countless missionaries for thousands of years. And, it's a promise that I personally can give, having tried it myself.]