To set up the services you offer, head to Practice > Setup > Services.
You'll then see at least a couple of example services, and a button in the bottom right corner labelled "Create Service"
Clicking on this will open a new screen where you can enter all the details for this particular service. The required fields are as follows:
You will also be able to select whether this service is available from all locations, or a selection of specific locations.
There are a number of optional fields that you can leave as is, or adjust to your liking, these are:
You will also be able to decide if you would like this service made available for online bookings.
You can also see a graph showing booking statistics for this service over the last month.
After filling out these fields, click "Create Service" and this service will now be available when adding appointments to your Diary.