Forza Painting?

so I bought forza and managed to make a pretty cool design, but then I saw some pics of of other custom painted cars and they had pictures of the simpsons, anime and dragonball Z on their.

So my question is how do you get your own pics to be able to be painted on your car?

alltight thanks men because I thought I would be able to take my customs picks and paint them on my cars and it would be a waste of time trying to make something nice out of those pics provided