Life in prison theme

The book I'm writing about is life in prison. The author is Stanley "tookie" Williams. This book is about an inmate who went to prison for life. Hes in prison for life because he did armed robbery and killed 2 people. He's writing books for teens because he doesn't want others to end up in prison like him. He is trying to make a change. In page 10 it says "he wanted to write books for kids, telling them why they should not join a gang" if you do this kind of stuff you will get consequences. This shows that you have to be good or else you'll end up like him and its a bad place where he's in.