1. Select one of your own photographs. It works best with a subject on a solid background, but feel free to experiment.
2. Remove the subject from their background and copy them to a new layer (Ctrl J.) If you're not sure how to do this follow this tutorial (you can stop at 4 minutes, because the rest shows how to do something that we're not doing.) https://www.youtube.com/watch?v=vru8BoENiHQ
At this point if you prefer to watch a video tutorial scroll down and watch the video posted below. If you feel comfortable reading directions continue with #3.
3. Go to the new layer that has a cut out and add a layer mask.
4. Mask (paint black) the subject so they disappear completely.
5. Use a small brush with 100% hardness and white paint to unmask (paint white) to reveal the subject. Do this creatively.... scribble, make polka dots, whatever looks interesting to you.
6. Add a drop shadow on that layer.
7. Duplicate that layer, paint the mask all black again, and repeat (this step adds depth.