Gerry - The picture of my little bird is located at www.photobucket.com. But another website image host could be used if you have one available. The "IMG" address is then copied and pasted into the signature file you find listed on the LH side when you look at the Control Panel page. Obviously, you have to be "checked in" at the timeI spent some time whittling on the image and the size of image before I sent it to the photobucket site. Can't remember exactly what size it is but it was about 450 pixels on the long side when I sent it there. There is a provision in Photobucket to halve or quarter the image size once it is there. I may re-do mine to make it smaller.
Hope this helps .........................