Rules to Go:
The basic objective of Go is to surround as many intersections on the board with your stones as possible. While this sounds simple, there are several additional rules that add great depth to the game. A good free online guide to playing Go is The Way to Go by Karl Baker.
For reading material, many frequent members of the Go Club learned to play Go through reading Janice Kim's Learn to Play Go: A Master's Guide to the Ultimate Game (Volume I). It's a very informative and well put together book for beginners, and its highly recommended.
However, the Go Club is always wiling to teach beginners the rules of the game. This reading material is very helpful, but the best way to improve at Go is simply to come play with other Go players.