Just get yourself down to the local track.
Your motor doesn't strictly fit into any class (except perhaps modified) but I am sure the track will let you run in the most appropriate class until you get a taste for racing.
A couple of tips...
1. Arrive at the track prepared. No point spending the race meeting working on your car and catching up with charging when you should be driving.
2. Focus on driving clean lines. Don't get distracted by battles with other cars, battle yourself and the track. Nobody ever went fast by missing apexes and crashing.
3. Enjoy it!