You can add one by:
Step 1: Go to My Control Center
Step 2: Click on Edit Profile
Step 3: There is a little box that says My Photo. Make sure the Private button is not checked if you want it to show on the boards.
Step 4: Copy the url of your photo or graphic into the box below "my photo" (You do NOT have to resize this photo -- EZBoard will automatically limit the size.)
Step 5: Scroll to the bottom of the page and click Save Changes.

