Paint jobs?

So I downloaded this bad ass paint job for my Dodge Viper. It’s green and the front of it is black but the black fades off into the green. But that is just on the front of the car. I can’t change the colors because its a downloaded art. So my question is, How do I achieve this on my own? It doesn’t look like its a decal on the front so im not completely sure what to do here. any help would be greatly appreciated.

it is done by decals, the one you need to use is under gradient shapes. Mate that up with a block of solid colour.