well this is what i do
1.Make a photobucket account.
2.Upload image to photobucket(name doesnt matter, no editing required)
3.Go to albums and hover cursor over image and a pop-up should come up below image.
4.Copy the img code.
5.Go to mpgh and then go to the user cp
6. Click on Edit signature.
7. Paste img code into the box.
8. Save signature.
Not very detailed and there might be an easier way but thats how i do everything, myspace, mpgh and other stuff.