JOEL - According to scientific evidence we know that thousands and millions of years ago there were dinosaurs and animals and something that had the appearance of humans, but through the scriptures we only know that it has been about 6000 years since Adam left the Garden of Eden. We don't know much more about how Adam was created or what happened before that.
In 1910 The First Presidency issued a statement on Evolution which you can read at this page.
The statement generally explains that Adam is the first man and the progenitor of the human race. Exactly, how he became the first man is something God hasn't told us yet.
The subject of the origin of man must be sufficiently nonessential to our salvation, otherwise the Creator would have told us more about it in the scriptures. The scriptures are more concerned with why man was created, not how, although the Lord has promised that he will tell us when he comes again:

"Yea, verily I say unto you, in that day when the Lord shall come, he shall reveal all things.
Things which have passed, and hidden things which no man knew, things of the earth, by which it was made, and the purpose and the end thereof Things most precious, things that are above, and things that are beneath, things that are in the earth, and upon the earth, and in heaven.(D&C 101:32-34)

Theologians, including Latter-day Saints, have come up with several theories of their own to explain things, but I am afraid we will have to be content to wait and have faith in both scientific discovery and in the revealed word of God; that eventually the two will harmonize together into one ultimate answer to this question.
I answered a similar question regarding dinosaurs at this page.