There is another way, tho I see that you have one now, but if you find one you like and it doesn't stand alone on a page, ( now this can trickey, some are protected, so I stick em in my photobucket.com), right click and you'll see properties, click on that........see the url? copy and paste that to either the avator area in your profile, or if you use photobucket, use the url it gives your picture that you have saved picture as......... and uploaded from your computer,
You can do with sigs too, but you have to use the image tag from photobucket.
www.photobucket.com