To add multiple calendars to your primary calendar,
Click Here for a tutorial.
Step 1: By default, we will display all your calendars in an Overlay Calendar view, which will merge and color code all calendars into one calendar.
Step 2: If you do not want to see a particular calendar, click the Calendars dropdown menu.
Step 3: Click the calendar you do not want to see to uncheck it. In this example, we don't want to see the "Personal" calendar, notice how it is unchecked after you click it.
Step 4: To view the calendar again, click the Calendars dropdown menu again, and click the calendar you want to see, notice how it puts a check next to it after you click it.
Step 5: If you prefer to toggle back and forth between different calendars instead of the overlay view, simply click the View menu and click Overlay Calendars to uncheck this option.