Guest tutorials » Gimp » Rainbow edges
First you start with your picture open in one window.
Then you open a new window and pick a color or pattern (patterns look better in the end) using the circled area and pick the paint bucket tool, also circled. make sure that whatever you decide to use (pattern or color) is selected in area 3 on the main gimp tool box.
Click on your image and it will fill with that color. next click the first tool at the top that is of the shaded rectangle. Select how much feathering you want on the edges. then drag a rectangle around the part of the image you want to use.
Copy and paste it into your solid color or pattern background, and it fades into it.
(c) Midnight Blue (2176208)