If the image is not copywrited(sp) or you want to use it anyway.
1. right click on image and click save picture as (save it somewhere you know where to find it)
2. click on the grey profile button(just under the Allotments 4 all logo) at the top of the page.
3.on the left under Modify Profile select Forum Profile Information .
4.on the right, click on I will upload my own picture: then browse and select the picture you saved in step1.
5. at the bottom of the page click change profile
Hope this helps
Neil