1. Open Outlook
2. Click the ... icon/button to the right of the word Tasks at the very bottom-left of Outlook, then click the Folders option in the menu to go to the Folders view
3. In the left hand navigation pane (where all the mail folders are shown), scroll down to Public Folders (should be at the bottom), click the small arrow icon to the left of Public Folders to expand it, then expand All Public Folders
4. Under Public Folders, Expand the folder with the name of your company using the small arrow icon to the left of the folder
5. Right-Click the calendar (or other item such as contacts folder) you wish to add, select Add to Favorites, then click the Add button in the box that pops up
6. The calendar will now appear as an option to select and use in your main Calendar view inside Outlook (if this was for a Contacts folder it will appear in the People tab)
NOTE: For Contacts folders, you will need to set them to appear in your Address book. To do this, after step 6 (add to favorites), again click on the Contacts folder, select Properties, click the Address Book tab, check the option that says 'Show this folder as an e-mail Address Book', then click OK.