Open Outlook and go to the Calendar view
Select Home
Click Add Calendar
Choose From Address Book or Open Shared Calendar
Search for the person’s name
Select the calendar you want to view
Click OK or Open
If you have permission, the calendar will appear alongside yours
To view a shared calendar in Outlook on the web, go to Calendar
Click Add calendar
Select Add from directory or Add from people
Search for the person’s name
Select their calendar
Click Add
If you do not have permission, ask the person to share their calendar with you
In Outlook desktop, you can also use Open Shared Calendar from the Home tab
Enter the name or email address of the calendar owner
Click OK
Switch between calendars using the left panel or calendar overlay options