Open Google Calendar
Click the gear icon and select Settings
In the left panel, choose the calendar you want to share
Under Share with specific people or groups, click Add people and groups
Enter the email address of the person you want to share with
Choose the permission level
Click Send
To make your calendar public, go to Access permissions for events
Check Make available to public
Choose the visibility settings you want
Copy the shareable link if needed
Send the link or invite to the people you want to share with