When I put gas in my car it quits and dont want to start. I was wondering why?

what quits and doesn't want to start? the filling of tank or car

Most likely it is your canister purge valve, my wife's car had the exact problem, and this took care of it. You can purchase one online, or at your local parts store. It's not super-easy to replace, but can be done with some automotive know-how.