Hi there, hamasnk358.

At the bottom of that page to which you're referring, you'll see a "Browse" button; click that, browse to the image you wish to use, then once it's selected, click "Save Changes". If, for some reason, that doesn't work for you, you can upload your chosen image to a popular image-sharing website, and then paste its direct link into the "Option 1" area of the avatar page. (just above the browse button)