DECAL help.. please

[Norcal_51]

ok before i even post.. i did ask this Q in decal tutorials but i never got a respone... but i am making a track and can not figure out how to add the decals, to make the racing lines and such... do i download them? make them? and how do i ad it to the track.. when i click decals it looks clear and i cant figure out how to paste it to the track.. can anyone help?