My guess is that you are referring to the edges?
If you are looking for digital solution in photoshop:
1. Backup your image
2. create a layer of complete white underneath the photo
3. increase the canvas size about 10% so the photo now apears to have have a large white border
4. Use the eraser tool to erase the background - use different types of brushes to get the effect - there is 'rough edge' brush that should be able to duplicate the effect.
5. Alternative: Instead of the erasing - you can also use the white brush to paint untop.
Try the darkroom forum if you are trying to do this with a film print good luck!