Having administrator rights allows you to edit any page or record on your site, add members to your site, and give other members administrator rights. This is done simply by changing the "Account Type" field of a member's settings to "Administrator". Only administrators can view pages like Payments, File Manager, and pages you set to have Administrator rights.

The only limitation to the number of administrators you can have is the number of members your current value plan supports. Therefore, all of your members could have administrative control if you allow them to.