1. edited image in PS
2. Choose rectangular marquee tool
3. place dotted lines (marching ants) around image as desired.
4. Mac: command C/command V
PC: whatever you use for copy/paste
5. Choose layers and fx at lower left
6. Choose drop shadow (you can choose others but this is a good one)
7. Layer style screen comes up. Normal or Multiply for mode/360 for angle if you wish frame all around image, I usually keep 'distance' at 0 and play with spread and size sliders. Play with opacity. You can choose colour of frame easily from the palette or by using the eye dropper tool on the image.
Have Fun! Share your results, or message me if you have questions.