Rally driving is a very dangerous sport, but it's also a very exhilarating one. If you're determined to become a rally car driver, then there are a number of steps that you need to take. First of all, you'll need to have a valid drivers' license. You'll also need a suitable car that you can use in rallies. You can either build your own car, or you can buy an already built rally car. The latter option can often work out cheaper, as you'll be buying a car that somebody else has already spent time and money on building up for racing purposes.
If you're serious about becoming a rally driver, it's a good idea to start out by joining a local motorsport club. Whether it's for SCCA-style rallycross or stage rallies, getting involved will help you meet people who can point you in the right direction on your quest to compete. You'll also be able to volunteer to help out with service crew duties at events, which will give you a chance to get a feel for what it's really like to be a rally car driver - you won't actually drive but you will be right in the middle of things.
Of course, if you can't afford to splash out on a proper rally car, then the best way of experiencing what it's like to be in a real rally is to give co-driving a go. Sitting in the right seat navigating for a driver puts you directly into competition at a stage rally, so all that drifting, jumping and gravel-slinging you saw on TV can be experienced firsthand.