[96SEChick]

Welcome to the wonderful land of auto-x! Taking a class is a great idea--especially if you are new to the sport. And, since you are only 17 (not bashing your age--read on)--what you learn about controlling your car during that class will help you a lot in every-day driving on normal roads in traffic. This is only my belief and opinion, of course. But hopefully it will be reality!

do i need to have a licence to do it?

No. As long as you have a valid driver's license to show them (if they even ask for it), you are fine. You don't need a racing license to auto-x. If you were to be on the track at the same time with other cars (such as a "high speed touring" event for example), you would probably have to get a racing license. But, not with auto-x. They make it very simple and inexpensive to participate.

do i have to decide what class i should compete in before entering, or will they tell me?

More than likely, you will be G-Stock if your 240SX is stock. They changed the stock 240SX from E-Stock to G-Stock in our region last year and it's probably the same nationwide. The G in G-Stock doesn't mean anything significant, if it even means anything at all. If you're not sure what class you'll run, ask the officials at the event and they will find out for you.

is there a minimum age, b/c im 17...?

Since you are under 18, you may have to have one of your parents sign a waiver stating they approve of you to be at the event and hold no liability if something happens. You should call your local SCCA club and find out what the coordinators/officials say. Since you have a valid driver's license, I don't see a problem, but since you are still under 18, you are probably still considered a minor in Missouri, and may have to go through a few extra steps w/ parental consent stuff in order to participate and race.