If you refer to an avatar, wherever you like; find a picture of someone you want representing your character and upload it somewhere. If you poke around in the Classifieds on the right menu you will also find people advertising their own images in the Artwork and Hosting section.
Use HTML, as I told you, and enter it into the textbox on your character profile page. I have already explained where you can find the HTML tags that you can use. If you are having trouble with this you will need to explain what problems you are having, or what it is you do not understand.