Tap an event to view its details.
If no reminder is set, tap the Add reminder icon to automatically add a reminder for 10 minutes before the event.
If a reminder is already set, tap the Add reminder icon to set more reminders for the event.
Tap the Time field that is displayed, to set the length of time before the event that you want to be reminded of it. Tap the Notification field that is displayed to set how you want to be reminded.
When the time comes, you receive a notification about the event.
You can use Google Calendar on the web to configure additional reminder settings.