Only to get a good border, I had to paint the side, then select the transparent cells, fill those with black, and select inverse again to get the original painting on the side, and delete. Then, I could use the transparent cells on the side to make my border. (A bit of a pain. There is probably an easier way.)
And I added a layer at the bottom with the color black for my background color.
I also added a texture and followed my standard texture protocol...which in a nutshell is...
- Add the layer I want to texture, choose blending options and change the blend mode under "General Blending" to my liking.
- Create a copy of my original image. Choose Alt-Add Layer Mask (the circle button at the bottom of the layers pallete). Paint on the mask with white to bring clarity back to the main subject.