I s*ck at PS too, but after a while and some reading I made a skin.
If you just want a 1 color car with your name in a different color, you can do that even in mspaint.
Get the corresponding .jpg for your car, put your name on boths sides, give the rest of the template the color you want (just zoom in and paint everything except your name). You can do that in a rough way, everything that isnt supposed to be painted wont be after you apply the skin to your car (so dont bother about where the windows are, or where the bumper stops)
Once you apply it to your car it all gets bright and shiny and looks a lot better then when you view it in mspaint. Have a look at a few skins in your skins folder and see if there's something you like there, maybe you can edit one of them with your name on it..