How do I race cars??

No way around needing money. Even the kids who get sponsored in karting who start racing when they're old enough to walk still need to have money invested in their racing development if they're going to go pro. Trying to get into it at your age, with no money, will require a lot of dedication and hard work. If you're more interested in road course racing, I'd suggest taking the path that many of us who like to race (but aren't rich) take to have fun at the track - start out running your car at local track events through an organization like NASA (http://www.nasaproracing.com), SCCA (http://www.scca.org), Hooked on Driving (http://www.hookedondriving.com), etc - essentially, any organization that has instructors. Get as much seat time as you can and listen to your instructors. Also go out to the karting tracks in your area and practice what you learn from the instructors, attend some autocross events (spectate and compete - ask for ride-alongs). Pick up some books and read about driver improvement, watch Youtube videos, etc. Track time isn't cheap. Expect to pay something like $100-150 for a single track day - that's just the event fee, not fuel, brakes, tires, etc. This can obviously get expensive really quick. To save money, volunteer to help staff the events in return for track time - work the flagging stations and the grid. I know NASA offers this. Of course, if you don't have many tracks in your area you might have to drive quite a bit to get track time. If you have a skill that the track ownership or racing organization could benefit from (like graphic design or web design), look into some barter options with them - e.g. trade some track time for design work. Once you build up your skills more you'll want to start competing more in autocross and time trials events. The time trials events will give you experience with being on track with other cars going full bore pushing for fast lap times. Once you start competing there's the opportunity to get some sponsorship, which can help you get some free/discounted parts and maybe even help you cover some entry fees (here's a good guide: http://www.carsponsorshipguide.com). The further you advance in your racing career, the more you'll need to familiarize yourself with sponsorship. Invest your time and effort into making yourself marketable, as this is just as important as driver skill. By the time you get to the point where you're doing some club racing in NASA or SCCA, you'll have found a lot of the answers you're looking for here. You'll also be surrounded by people who have spent years racing and you'll be able to pull from their experiences to help you get where you need to go. Always keep in mind; racing is a business. And it's a tough business to be in. You have to learn the marketing side of the business.

The cheapest way to start racing with no experience is http://www.chumpcar.com/ http://www.24hoursoflemons.com/ You can rent a seat in someone else's car. All you need is some safety equipment (helmet, etc.)