Click the button to bring up your profile - then look down the bottom for "avatar" - and link to a picture - it can be any .jpg/.gif etc (I think) just needs to be reasonably small.
Shout if you need more help.
If you are stuck, email me a digital picture, I'll convert it, host it on my picture site, and send you the URL to add to your profile to allow it to be displayed.
Adam