Towards the top you should see Forum Actions (New Posts - Private Messages - FAQ - Calendar - Community - Forum Actions - Quick Links)

Click on there and then you should see Edit Profile

On the left column under My Settings - My Profile - Edit Avatar

You can try uploading from your computer or you can upload the picture to the Trophy Room and enter the URL to it. It may take you a few tries to get the picture to the size needed to upload for an Avatar. My suggestion is to save the picture separately on your computer, open it using Paint and then go to Image - then Stretch and Skew to slowly down size your picture until it uploads successfully. Keep giving it a try by attempting to upload directly, resize and save, upload...etc. If you have trouble then you can send me a PM and I can try to give you a hand.