Many people like to personalize their posts or profile with their own custom avatar or photo. This forum allows you to have both an avatar and a photo (you can see that my avatar in the forum is one phot and the photo in the blogs section is another).

If you want to change your avatar, profile picture or signature you can do so by selecting the "Forum Actions" button in the tool bar just below the section headings. Then simply select "edit profile" and then "edit avatar" or "edit profile picture" or "edit signature".

You will find many other custom features in there to play with as well.