Use The School Day page to set up how your day runs - the lesson/period times.
You do not need to enter breaks - just the periods that you want rooms to be able to be booked on.
Period times should not overlap other periods.
When adding a Period, tick all of the weekdays that it is applicable to.
If you want rooms to be available "out of hours", some people find it useful to add "Before School" or "After School" periods.