Solution

1. Go to Administration >> Appt Schedules
2. Click on New Schedule
3. Enter the public holiday's date in the Applies From/To fields
4. Tick the Leave Period checkbox
5. Select All Clinicians in the For Clinician field to show that the public holiday applies to all staff
6. Enter a name in the Leave Description field
7. Click OK to save and add the public holiday

The example below shows how to add New Year's Day as a public holiday:

Go to Appointments to see the public holiday in the calendar:

Note: The colour displayed for holidays can be changed in the Site Settings window.