When creating your Signature.. go into user cp at the top, then click on edit signature.. you will then see its gives you the option to upload from your computer.. when it has uploaded, click insert signature, then save signature!
Its worked If you want to get your Sig pic in the middle, rather than to the side.. go into edit signature again and then click on centre.. thats the middle one next to the B I U.. then click save and it will then be in the middle