You can add or change your profile picture in Sisu using the desktop web app or in the mobile app.
Adding or Updating Your Profile Picture in the Sisu Web App
Click Account (upper right corner)
Then on the left you can add or update your profile picture.
Adding or Updating Your Profile Picture in the Sisu Mobile App
Go into the Sisu Mobile App and tap on the MORE tab (bottom right corner)
Tap on My Profile
Tap on the circle where your photo will go and options will pop up with where you'll import your picture from
Upload your photo and you are all set!