You can't upload an avatar directly to the forum, but if you have a photo account somewhere else like flickr or photobucket you can use that as your avatar.  Just upload your pic to flickr for example and then copy the URL.

Then make sure you're logged in here and click the "profile" tab at the top of the page.  Then click on "forum profile information" in the lefthand menu.  Once here, you should have two options - "personalized picture" and "I have my own pic."  Click the radio button for "I have my own pic" and paste the URL of the picture you uploaded to flickr.

Hope that helps!

The only thing I can think of is that maybe you're pasting the URL to the page your picture is on and not to the picture itself.  To get the URL of the picture itself, pull up the picture in your browser, right click on it and click "copy image location" and paste that into the avatar field.  If that doesn't work, then I'm afraid I don't know what the problem is!

I saw that confoundit was shown as guest (as I had never seen that before), but in this thread confoundit comes up as newbie