To get events on the calendar, you at least need to have a title, start/end time, and unique ID. That means you can start by setting up your DB like this.
In addition to the above created event properties, you'll also use the Uniqe ID created by the Bubble DB. Again, you dont need to do anything to have these created, Bubble takes care of this for you. You will, however, need to make sure to use this automagically created property when filling in event fields while using the calendar element.
As your app becomes more complex, it is feasible to assume that you'll want to associate more and more data with events. Using the built-in Bubble Database, you could always click an event, get it's uniqe event ID, then go do a search and recall some data related to that event. OR, you could load that data into the calendar with the event itself. This makes the extra info immediately available and avoids the need for extra calls to the DB thus reducing overall server load.
Other possible event properties