According to this story, the Immortan’s real name is Colonel Joe Moore (hence those medals), a veteran of the Oil Wars, and later, what’s referred to as the Water Wars.
The second half of the issue is likewise a prequel, this time charting the rise to power of Immortan Joe himself. It’s short and sweet, and lends a bit of insight into what life is like for those living on the ground floor of Immortan Joe’s empire.
The first focuses on Nux, revealing how he became a War Boy, and the strange sort of familial camaraderie that binds that group together. Tattooed on his entire body are stories, or “Word Burgers” (the synopsis for Fury Road mentions it’s “based on the Word Burgers of the History Men,” George Miller is very fond of silly words). Both are narrated by a “History Man,” apparently a living surrogate for a lack of books and recording devices. The first issue features two stories, both set decades before the events of the movie. Some story details follow, so if you don’t want to be spoiled, just know that the comic is a pretty interesting addition to the world of Mad Max, and worth checking out if you’re interesting in exploring it further. If you’d prefer more concrete answers though, or you’re just looking to explore that universe a bit more before the eventual sequel, there’s a new Vertigo comic series that begins today that should help.
Mad Max: Fury Road doesn’t waste much time with exposition, leaving you to create your own backstory for the crazy world we glimpsed in that movie (although we did try to make sense of some of it here).