Hover over "Settings" in the bottom left side menu and click "All Settings"
At the top of your settings page, you’ll find your current avatar. Click on "Change" beneath your avatar picture to upload a new one.
Alternatively, to remove your current avatar without adding a new one, click the X in the top right corner of the avatar:
If you do not see the option to change your avatar, check out this article to learn why: Why can't I chat or post in forums or change my avatar?
What size should my avatar be?
Your avatar should be square and at least 175 x 175 pixels to ensure it appears correctly across the site.
You can use any common image file type, such as .jpeg, .png, .bmp, or even an animated .gif.
If you use an animated .gif, the animation will only display on your profile page and not in other areas of the site, such as forum posts or during games.