Click "Calendar" in the left-hand pane of the Outlook window.
Click the "Open Calendar" button in the ribbon.
In the dialog box, click the icon next to the "User" text box.
Type the name of the user whose calendar you want to access and click "Find." The user's name will appear in the box. Select it and click "OK." Finally, click "OK" one more time to access the selected user's shared calendar.