You can change your profile picture by following these steps:
1. Click on the profile icon in the top left corner.

           
2. Click on "Frame and Avatars" and click on the Avatar tab                 

            
3. Either upload a profile picture or choose one of the avatars available.

How do I add my own profile picture?

To upload a profile picture, simply click on the first bubble and following the prompts to choose your profile picture.