How do you import picture and music into games?

[Thefreak121]

I don't mean replace texture , in nfs shift it allows you to import pics from memory card into the game to add decal n vinyl designs on the car, its not impossible and it is related to ppsspp , not to be rude , if you have played nfs on a psp you should seen that function on the game, you can do it on a normal psp but I want to know if its possible on the emulator, because its part of the game function. It just need to find the part for picture in the memory card folder . So that it could load jpg pics on the game to add your own custom design.

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This what I'm mean by loading pictures.
I want to change yellow stuff , the game has the a function that allows you to import picture into game so I can add my pic that I can us as the yellow stuff on the car.