Google's Instructions:

On your computer, open Google Calendar (

- You cannott share calendars from the Google Calendar app.

On the left, find the "My calendars" section. You might need to click it to expand it.

Hover over the calendar you want to share, click More More and then "Settings and sharing"

To share with individuals: Under "Share with specific people," click Add people.

Add the person or Google group email address. Use the dropdown menu to adjust their permission settings. Click Send.

The recipient will need to click the emailed link to add the calendar to their list.