Not sure about the screen name. Think you can go to user cp and upload or choose and avatar. Haven't looked here, but that's how it's done on other sights. For images, if you use something like photo bucket, you add (WITHOUT THE SPACES)[ img ] insert image address and then add [ /img ] at the end. Same with quotes, etc.. [ quote ] add quote [ /quote ]
Remember ... no spaces between the bracket [ and command. I added the spaces so you could see.
Badmofo, no worries, I've been in to computers my whole life and this stuff is still confusing as heck much of the time. I just put up a how-to vid to give you and others an easy walkthrough to follow on how to setup an "avatar":