First, open up your image. Choose your magic wand tool, and select your whole image. (use wand to click an empty space anywhere in your picture)
It should now have a running border around it. (marching ants?)

Go to Select>>Modify>Expand.

Put 6 pixels.

Fill the space in with whatever pattern you want.(Edit>>Fill) SPAZZ! Now, you have a patterned border! You can also fill it with a solid colour if you like.
Please link back!