Buttons and menus are named exactly as the app shows them.
Steps
Add an event
Tap the plus on the Calendar tab, or press C anywhere, for a timed or all-day event.
Where: Calendar tab
Make room for the month
Hide agenda folds the list away when you want the month to yourself; Show agenda brings it back.
Where: Calendar tab › Hide agenda
Subscribe to a calendar link
Paste an https:// or webcal:// link and choose Subscribe to a link. Refresh subscription pulls in the latest.
Where: Settings › Integrations › Calendar
Import or export a file
Import a calendar file, or paste its text, to copy its events in once. Export mine saves your own events as a calendar file.
Where: Settings › Integrations › Calendar
Connect Google Calendar
Connect it from the web app and the connection works on your other devices too. Sync now fetches changes straight away.
Where: Settings › Integrations