Help Center - How do I add an avatar/blinkies to my forum posts?
To add an avatar to your public profile (which will appear on your forum posts also):
Go to your Account Settings
choose Settings from the dropdown menu under My Account in the toolbar at the top of the site.
Scroll down to the Public Profile section (or click the link at the top of the page to go there directly)
Click " to the right of the "Change Icon" space. This will let you browse your hard drive to find the picture you want to upload.
Make sure your picture is a valid file type (gif, jpg, png), and is smaller than the maximum filesize (30kb), and smaller than the maximum allowable dimensions (75px x 75px).
This will also work in the Forum Settings to add graphics to your forum sig.