Hi Dazz,
You need to host the photo somewhere first. Either Flickr.com or postimage.org (both free photo hosting sites) then login and go to your profile page (link is at the top left of the page once you've logged in)
Scroll to the bottom of the page until you see "Link to off-site Avatar:" That's where you need to post the address of your photo (it'll be something like
http://www.postimage.org/image.php?v=PqbN33 if you're using postimage.org.)
Then just hit submit.
If you want to use one of the standard avatars they're in the same place, just click the 'show gallery' button and choose one. If you have any trouble just email the pic you want to use to
admin@wabowlscum.com and I'll fix it up for you.