Hi Craig,
To add a photo I... hit Reply to post, click on the paperclip, click browse and choose the picture you want then click on upload. Close this window, click on paper clip and click on the attachment. There it is! You can add pictures to your Avatar or signature the same way by going into user cp at the top of the page to the right and click on edit signature or avatar. Hope this helps! Good luck, we would enjoy seeing your car!