To add instructors go to Manage > Instructors > + New Instructor. Here you can also setup their rates in the Rate Setup tab.
An instructors schedule can sync between their Associations if they have more than one. For example: You have two Organizations and your instructor works at both, when someone books a reservation on one Organization it will reflect on the other Organizations schedule. This will also hold true for their work availability.
Note: There is about a 15 minute lag time for sync.