You can't gift credits. What people do is they put a cheap 5,000 credit car on the AH for the buyout amount they want to gift. Then they send the car back to the seller.
Keep in mind if your credits aren't legitimately earned, both parties could be banned from the certain aspects of Forza's online. --- http://28.media.tumblr.com/tumblr_ll5kqm3U111qbmz2jo1_500.gif Head slapping fanboys since 2006. Now playing: Skyrim, Forza 4