How to add a biography to your profile
Click on Settings in the menu
Select My Profile
Click on the profile heading in the menu
Add your Biography into the Public profile section and save.
Alternatively if you were an office administrator, you need to
Click on Settings in the menu
ClICK USERS
Enter into the profile that you need to update
Click on the profile heading in the menu
Add the Biography into the Public profile section and save.
Attached also a short video you can look at.