Open Google Calendar: https://calendar.google.com
Click the gear icon (Settings)
Select “Settings”
On the left, find “Settings for my calendars”
Click the calendar you want to share
Select “Share with specific people”
Click “Add people”
Enter the person’s email address
Choose their permission level (See only free/busy, See all event details, Make changes to events, or Make changes and manage sharing)
Click “Send”
To share with a group, add the group’s email (if applicable) and set the permission level
To share publicly, under “Access permissions,” enable “Make available to public” (only if you want public access)
To stop sharing, return to the shared calendar’s “Share with specific people” section and remove the person or change permissions