Recently I was having problems with the white edges around my Long Service award effort. It looked like this:
As you can see the picture has a white background. With Fallen's help I managed to remove the white background using GIMPshop by making the picture transparent and saving as a PNG file. Although this method worked for me, it didn't show up right for others as certain versions of Internet Explorer don't support PNG transparency.
However, I managed to find a simple way of solving this problem using Adobe Photoshop without transparency.
When you're finished your project and you're ready to save, select your 'Background' layer.
You'll notice there is a little padlock which means you can't move the layer, but you should be able to delete it. Right click on it and select 'Delete Layer'.
Now that the Background is completely gone, it won't bother you.
Note, however, that you CAN NOT save as a JPEG if you don't want the background to show up. JPEGs will fill the missing space in with White and so you will still be left with the white edges. Click 'Save As' and save your project as a PNG file. When you upload it, it will no longer have the white edges around your project, and will show up like this: