This might be what you are looking for.
Find an image that you want to use as your avatar.
Then click "Profile"
Then Click "Forum Profile Information"
You should see something like this for avatar's
Now if you have an image on your computer you want use "I Will Upload My Own Picture", then browse and find it. Then once it is in go to the buttom of the page and hit "Change Profile", If you found one online use "I have my own picture" and enter the url to the image.