Timetable Construction is automatically available to any user logged on in the role of Principal. However, it can also be made available to other users in the 'Users & Groups' screen.
Go to 'Settings' > 'Users & Groups' > 'Permissions'. Here you can drag the 'Access to timetable construction' permission into the relevant user column. Any user in this category will then have access to the timetable construction screens.
For full instructions on how to use the Users & Groups feature, click here.
To access Timetable Construction, expand the last red tab (3 lines) and select Timetable Construction from the list.