How do I use templates and history?

You can use both.
Touch and hold a date on the calendar, and "Templates", "History", and "Background" appear. In "Templates", you can register your frequently used events with "Add a Template", and "History" shows the events you added in the past. You can add an event with the same content just by tapping it, which is handy when you enter the same event many times at once.

You can choose which details (time, location, notes, and so on) are copied from history under "Items to Copy".