Before you begin to add a shared calendar, make sure you have access to it.
1. From Outlook 2011 go to Calendars, then click on the Open Calendar icon in the menu:
2. In the next window, click on the directory icon.
3. Type the name of the owner whose calendar you want to access, select the person from the list, and click Ok.
4. Click Ok on the following prompts and you should see the person's calendar in the list of calendars in the right panel of Outlook. Check the checkbox next to their name to have their calendar items appear in your calendar.