Try these for the rule books and other interesting info -- how to get started, car classes, schedules, etc.
www.azscca.com The rules are on the left side of the home page under club racing, cars and rules.
www.nasaaz.com The rules are at the top of the home page under rules.
www.proautosports.com The rules are on the left under rule book.
SCCA and PROAUTOSPORTS both have events in Phoenix on 26-27 Sep -- SCCA at Phoenix International Raceway (not too far from you) and PROAUTOSPORTS at Firebird Raceway. NASA has an event at PIR on 3 Oct. You might want to check out their events. It might give you some ideas. Good luck.