There are two parts to it: "Add people to Geckoboard" which allows you to invite new admins individually or in bulk and "Manage people" which allows you to resend invites, delete admin and view-only users, control the access of "view-only" users and promote view-only users to admins.
To invite team members as admins, simply type in their email address i.e. firstname.lastname@example.org (comma separate email addresses to invite more than one team member at the same time) and click "Send invite".
To invite team members to access dashboards in view-only mode, use the dashboard share feature.
Tip: Once "view-only" users are created, you can use "People" to give them access to more dashboards.
The "managing people" view is made of two tabs so you can manage admin and view-only users separately.
From the admin tab, you can use the right menu to resend pending invites and delete admins.
From the view-only tab, you can use the right menu to resend pending invites, delete view-only users, control the access of "view-only" users and promote view-only users to admins.