I taught myself to use the PC on a black car. The black car is the BEST teacher, bar none. Don't worry about learning to use the orbital. It isn't hard, and there is enough info on this board to practic ally guarantee you success the first time out (search on "technique"). and the good news is that even if you don't get exactly the results you were looking for, you won't DAMAGE anything (unless you DROP the orbital on the car, or other such acts...) You just come back here, search, ask questions, figure out what might have gone wrong and then try again.
Just to get used to the weight, balance and general handling, I'd recommend you start off applying waxes, polishes and/or glazes, but NOT swirl mark removers or anything more aggressive. When you're comfortable with that, move up to the more abrasive stuff.