Forum teck help

[Clem Kadiddlehopper]

I started a group on the forums - Traditional Knife Collectors Group
Would like to add a photo - The one when you visit the group and it shows in left hand corner.

Any one know how this can be done.
I've seen other groups with an AVATAR - I guess is what you would call it?
Or if you hold your mouse over where it goes - it says Group Icon....

Help?

Thanks!