If you have good experience and want to get into club racing, contact your local BMWCCA chapter and try to get enrolled in the next available Club Racing School. It's a good intro to racing and US tracking. If you just want to have cun and track your car, you will probably have to establish your experience/credentials at a couple of events with an instructor and should then be able to run in about any group. BMWCCA and PCA for education and learning, Chin, Trackdaze (and others, I'm sure) for just going our and having fun and getting some seat time.
2004 330Ci: Sport Pkg, TiAg, gray leather, UUC Swaybars, H&R Springs, Blistein shocks, UUC SSK, Autobaun miles (Euro.delivery)