Here is a pretty good article on PID theory and practical application for quads.
http://myfirstdrone.com/tutorials/ho...-a-quadcopter/
Your flight controller may not even give you access to PID's though. Start with reading the manual before anything else. Your best settings will depend on a lot of factors, the biggest of which is the response time of the ESC's you have and the overall balance of your quad. The good news though is that a quad doesn't have to be perfectly optimized to get out and have fun flying. If it wiggles a little on certain maneuvers who cares? You can improve it as you go forward and learn more about it.