In the web UI, click on the calendar icon to view your calendars.

1. Click the plus sign next to +New calendar
2. Choose New calendar
3. Enter the name for the new calendar
4. Press the Enter key
5. Click the three dots to the right to edit configuration.

1. Click the share icon next to the calendar you want to share. That is a little “one to two” icon
2. Click the box that says “Share with users or groups”
3. Type name of user/group to share it with. Hint, users have one person icons, groups have two
4. Put a check box in 'can edit' to allow the user to make changes
5. Click anyplace else to update the permissions

The calendar will now show up on other users web interface, and can be added to their external devices

In most cases, you can enter the URL of the nextcloud instance and add it to a caldav app. The app will then use your username to determine the correct base URL's for all calendars, then allow you to choose from the list of available calendars to you.

However, clicking on Calendar Settings (lower left, gear box) brings up a menu which allows you to copy the primary CalDAV address, or a special CalDAV address specific to MacOS and iOS.

Additionally, you can click the three dots next to an existing calendar and choose “Copy private link” if you only want the URL for that specific calendar (may not work on Apple devices).

Both of the options above copy the URL's to the clipboard.

1. Click any unoccupied space in the visible calendar.
2. A form will pop up within a few seconds (depending on the speed of your browser)
3. You can enter the event title, select the calendar, choose the date.
4. Uncheck All Day to put in a start/end time.

HINT: clicking the More button gives you a detailed form where you can fill out a lot of detail, including making the event recurring.