Once you have the picture ready, load it to a photo hosting site, such as imgur.com. Then copy the generated "forum" or BB code. It will be the code with in the beginning. On the forums, click on the User CP link in the menu above. On the left hand side, you will see a link to Edit Signature. Click that and then paste the link you copied earlier and save. Just be sure the image is within the signature guidelines. Post here if you have any issues or questions.
