This is completed in the account that is accessing the shared folder
1. In Outlook click on File
then Account Settings and Account Settings again
2. Highlight the email and click on the Change button
3. Click on More Settings
4. Click on the Advanced tab and then Add
5. Type in the name of the email address whose folder you have been given permission to share
then OK
6. You will be returned to the previous window and the account name will appear under 'Open these additional mailboxes'. Click OK
7. You will be returned to the Change Account window, click on Next
then Finish
8. Close the Account Settings window
9. You will be returned to Outlook. The name of the mail box of the account who shared the folder is displayed below yours on the left hand side. Expand this and the shared folder is visible
If it does not immediately show you may need to close and re-open Outlook.