To add an avatar to your GoComics profile, you will need to log in to your account. After you have logged in, navigate to your "My Profile" page. Here you will see your display name and bio (if you have added one).
Click in the center of the avatar box, and the upload dialogue box will appear.
Next, select "Browse," locate the image on your device that you wish to upload, and then select "Submit." If the desired image meets the avatar requirements, you will see a "Success" message.