As far as I know, anyone qualifies for Nationals. And Nationals is the qualifier for Worlds. I don't know of any NorCal events, but there is plenty in SoCal. Check the Canyon Lake Wake Board Club
www.wakeboardclub.com, or the Wakesports Unlimited Series
www.wakesports.com, or the Spring Valley Wakeboard Club tournaments. Try out one of these events and see how you stand up to the locals there, then buy a plane ticket and check out Nationals.