Here are some books I liked when I was your age. Some are fun, and some are serious:
The Giver-Lois Lowry
The Outsiders-S.E. Hinton
The Diary of Anne Frank
To Kill a Mockingbird-Harper Lee
Any of the "Joey Pigza" Books. They're an easy read, and just generally fun.
The Chronicles of Narnia-C.S. Lewis Any of the books in this series!