MoshPit

First you need to place the image you created in the following folder: \MTA San Andreas 1.5\mods\deathmatch\resources\gcshop
Where is says "File path or direct line". make sure that only has the pic name like
paintjob.jpg
make sure to select custom 1 from list
on "paint 1" change the base color of the car to white so that it shows, if its a  dark color u wont see it