California has plenty of places to learn how to hang glide and beautiful places to practice it. If you just want to experience it before deciding whether to take classes, you can take a tandem flight with an experienced glider. A good source for finding classes, organizations and locations for hang gliding in California is www.caoutdoors.com/Hang+Gliding-California.htm
One of the more comprehensive resources on hang gliding instruction is the US Hang gliding and paragliding organization - at www.ushpa.org.
They have a listing of all schools an dealers in the U.S. on the site ( http://www.ushpa.aero/schools.asp ).
In the SF bay area, I like Mission Soaring, see http://www.hang-gliding.com
You can start out by taking a tandem flight (from a mountain, or at an aerotowing park). But I recommend first signing up for an all day lesson. After a ground school session, you will run down a small hill and get airborn on your first day. It is an incredible feeling, and will tell you if this is something you have to do. The fact that you are only a foot or two off the ground doesn't matter -- you are in control and flying yourself. After you have done that, a tandem flight will be fantastic, because you will be able to take the controls and fly the glider while you are over a thousand feet in the air!