Open Outlook

Click on the Calendar icon

Under Shared Calendars, right-click on Shared Calendars.  Choose Add Calendar then choose to Open Shared Calendar.

In the Open Shared Calendar dialog box you can either start typing the person's name, or click on the Name button to take you to the Address Book.

In the Address Book, you can type the person's name in the Search dialog box and when you find the correct person, click on their name to hightlight it and click the OK button to add them.

Now you should see the calendar under your list of Shared Calendars