to race or test and tune on a road course with other cars on the track you need an SCCA competition license
to get a SCCA competition licence you need to attend a racing driving school, a properly prepped race car ( can rent them) and a licenced proctor ( instructor) to give the driving test.
look to spend around 3000-4000 to get all those things if you dont have any connections.
if you want road racing with out the cash outlay, look into SOLOI or SOLOII. neither requires special licensing or prepped race cars, you run a road course by yourself and you are racing against the clock. much cheaper for the beginner.