Go to the 'Admin'-settings in the upper right-hand corner, and through the left-hand menu, choose 'Team members'.
Click the 'add team member'-button to begin the process.
Enter the data for each new team member, and click 'Send invite' (or 'Add person' for virtual users).
Find, and edit all your team members on the list if needed.
These settings are only available to administrators of the organization.