I agree with flstf. Depending on how deep it is, you should gauge how aggressive of an abrasive you use to polish it out. For minor surface scrapes like it sounds like you have, I use Meguire Deep Crystal System Polish and wipe it off with a microfiber cloth; if it's a little deeper, I'll use a random orbital buffer. If it's worse, you move into the claybar area where you can take out quite bad scratches. Maybe you should read up on the recommended techniques, lots of car forums have good info ...or Meguire's site has some instructions too
http://www.meguiars.com/howtocenter/