Create an event
Open Menu, then TEAM & EVENTS. The item is called Events, unless you are a photographer, in which case it is called Sessions. Same screen either way. Create a new one from there.
Fill in the Event date, Venue, and Party size. There is a notes field for references and special requests.
You choose the state at creation. Confirmed puts it on the calendar. Still deciding pencils in a hold instead, with "Hold this date until" setting when the hold lapses.
An event is more than an appointment. It carries its own services, money, team assignments, checklist, day-of resources, documents, and gallery.