To add people click on the circle.
This action opens the area management of people in the circle. Enter the email address of the person you want add in this area and click on "invite".
Create a new area (circle)
To create a new area, click on the + icon outside the circle.
This action opens a pop-up to add name to the new area.
After creating the new area, click on it.
and insert the account email you want invite in this circle.