Torn paper edges

Two cardboard pieces in .png format. Apply your photo to the cardboard like this (I use PSP9):

1. Open the cardboard piece (you might have to resize it a bit depending on the photo you chose
   
2. Make a new layer, and paste your photo into this top layer
   
3. Delete areas of the photo, which is outside the area covered by the cardboard
   
4. Delete the areas of the photo, which covers the torn cardboard edge, with your eraser tool and a suitable brush
   
5. Set the layer blend mode to "overlay" on your top photo layer
6. Adjust the contrast and saturation on your top photo layer to make the photo look right. In this case I made the photo a bit darker and added a bit of saturation, but it really depends a lot on your photo, so play around with the settings until you get it right
   
7. Select the area outside the photo with the magic wand tool, chose selection, modify and feather (size approx. 3-5 pixels) and hit delete a couple of times to make the edges a bit smoother on the photo layer
8. Merge visible layers