Well, heres how to texture cars, open the car .blend file, split the screen in blender, go to UV image editor, and on the first screen, go to edit mode. The UV map for the car will show up on the UV image editor window. then, on the UV img window, click open image. Then find a texture for your car (RockCarred.png (if yur using Klayton's car) etc..). In the car window, go to textured mode, and yur car will be textured red.
I hope this helps, and its understandable.