Add your Google, Outlook or iCloud calendar
Calendar โ Calendars (the calendar button in its header) or Home โ Add your calendar. Paste your calendar's private (secret) iCal address:
Google Calendar: Settings โ your calendar โ Integrate calendar โ Secret address in iCal format.
Outlook: Settings โ Calendar โ Shared calendars โ Publish a calendar โ the ICS link.
iCloud: share the calendar as a Public Calendar and copy its link.
Events appear on Home and in the Calendar. Remove a calendar from the same dialog.