Photoshop users only:
1. Make 3 new layers on top of all the others.
2. Make a selection of the entire canvas.
3. Select the last layer (the one on the top)
5. Go to: Edit/Stroke
6. Make the color black and have 3 pixels, put it on 'inside'.
7. Go to the layer underneath (don't delete the selection, if you do then select it again)
8. Go to: Edit/Stroke
9. Color WHITE, 2px, inside
10. Go to layer underneath (last layer out of the 3)
11. Edit/Stroke
12. Color BLACK, 1px, inside
13. Set the top 2 layers on 'overlay'
14. Enjoy your new border! (Made a 14th instruction cause 13 is unlucky D:)