Go to view car and move the camera to the desired position and press X.
This will snap a photo of the car and will save to your PS3 Game Data Utility(whatever its called) as well as under your Photos on the PS3 "dashboard"(xbox guy not sure what to call it). Go to photos and youll find your photo in a folder that most likely is labeled by the month. Just copy that photo(press triangle for options) to a USB and transfer it to your PC and upload it to Photobucket, Imageshack or any other online media storage site. Then just copy it from your online album onto the thread of your choice!