Just connect your PSP to your pc with the USB cable. If you don't have one go to the nearby shop for cameras or computers. If it is connected your pc reconize the PSP and opens a new screen. If not go to: My Computer>Removeble Disc(Or something else, just try..). Open it, click on PSP and then PHOTO and put your pics there. If you want to make a map only for your pixel cars then just create the map there, like: My Pixel Cars..
(Do you also make tuned pixel cars? My fav:
PM Me about it or something if you wanna reply about this..)
