I have a folding screen that I want to turn into a photo display

You could decoupage pics onto screen.....easy to do with ModgePodge bought at any craft supply or walmart. You could do both sides....show no tape.

It sounds like you already know how to put pictures into the openings, right? Just want to decorate the rest of the screen? If that's the case, please, please just paint it a lovely color. Let the photos have all the attention. Decorating the background (the screen) diminishes the impact of the photo. I was in graphic design for many, many years. This was something we fought with clients about all the time! Your photos should be the focal point. Spend plenty of time arranging them and let the background stay in the background.