This should help you out.
Outline Object by Pyrochild
You Know how to get Plugins and all that, right?
Now for the Instructions.
If you need to out line the whole picture, increase you canvas size by 20 on both width and height, anchored to the middle.
Magic wand the white around the edges, then press delete.
Run the plugin at setting of your choice. I like a width of 2 to 5 depending on the image size
Magic wand any transparency outside the border, then invert selection.
Finally hit crop to selection.
I can update with pics if you need them.
PS: For the colored frame, magic want the border and replace with the color you chose with the paint-bucket.
If you need help with other things then don't be afraid to PM me. Or start a new thread.