there are two ways to upload your avatar.
First goto "your control panel" located under your log on name at the top of the page. Click on "Avatar Options" then
(1) page down to where it says "Your image avatars". Post the url from one of the pictures that you have loaded to your upload center or your own website if you have one next to where it says "Your avatar". Set width and height Max 64x64. Click "Add my own image as my avatar" Done.
(2) At the bottom of the avatar option page where it says "Upload your own Avatar" Click on "Browse" this will allow to the pick a picture from your hard drive. Double click on the picture that you want to use as your Avatar and the picture info should be in the address box now click "Upload". It is now saved in the "Pre-installed avatars" section on the same page. Find your picture and click on it. Then click "Add this avatar to my profile" Done. The only thing about using this method is that anyone can use your picture as their avatar also. If you want to keep it to your self use method One.
The reason you can see the avatar now is because when you uploaded the image the board was able to grap it from the same directory as the avatars. Therefore one way or the other you managed to upload your avatar to the server.