Answer:
1) Double-click the day of the event, and there should be writing saying "New Event". 2) Now click on this, and there should be a pop-up to the side with the details - along with "Edit" and "Done" buttons.
3) If you select Edit, you can reset the name of the event, change the time of the event, and make a message and/or sound set for whenever you like, as a reminder.