Adding a picture here is really easy! All you have to do is go to your profile, you can access your profile by clicking your username on the top right hand corner

Once your at your profile, right above your avatar and reputation points is a toolbar (Activity /Profile / Messages / Friends).

Press on ”Profile”, once your a new page loads up. Under your Mood/stock image will appear three options ”Public/Edit/Change Avatar”

Click ”Change Avatar”

Upload Picture.

There Ya Go!