To add an profile photo, first go to the manage your account, then click avatar.
Here you may upload your image. For gifs though, they MUST be 128x128 pixels and under the file size limit it shows on your screen. For non moving images, it will automatically center your image and use the center point as your profile photo. If that is not how you want your profile photo cropped, please be sure to crop it ahead of uploading it, so it will display properly.