Step 1:

Click on the “Google Calendar” button or the “+Google Calendar” at the bottom right of any calendar.

Step 2:

Click “Yes, add this calendar.”

Step 3:

The new calendar should appear in the “Other calendars” section on the left side.

Step 4:

If you do not want this calendar to appear, click on its name on the left side under “Other calendars”.  You can display the calendar whenever you would like.