In order to add profiles for your family members, hover over your name in the upper right corner of the screen. Then click Settings.
Select Family Members from the menu on the left.
Now select Add New User.
Enter your family member's name, and create a unique username and password for them.
Now they can log in to Mango Languages with the username and password you set. Later if you select their name from the Family Members page, you will be able to view their study progress.
NOTE: At the moment you can only create family member profiles in a browser and not in the mobile app.