Click Appointments > Services > Create > Service

Set the max number of customers.

Set the price, and consider whether the price is per customer (or not -- in this case, it should be much higher).

Lastly, consider if the service needs multiple teachers and if you want this to be a requirement.

Save when done and assign the service to the Appointment Boards it applies to.

Click Boards > then select a board.

Then click Services > Assign Service.