You may find the following items useful for playing this game:
Pathfinder SRD – The most complete reference online for Pathfinder RPG rules, errata, and some 3rd party content. I always recommend getting the core book at the minimum to support this great game but if you don’t have it available this site will give you everything you need.
Pathfinder Wiki – This is a great site for knowledge on all things Pathfinder. Use this site with caution though because not all things related here may be known by your character.