Click on "my profile" at the bottom of this page.
You'll see this:
To display a custom avatar go to gravatar.com and upload an image for the email address associated your able2know account. Changes will be reflected as gravatar.com caches and your browser cache is cleared. This can take anywhere from minutes to hours typically. Users with no custom gravatar have a unique image generated to help others distinguish between posts. Avatar sizes can be changed in your preferences or avatars can be turned off altogether.