.Note: You have to do this step in the Outlook application and not online
1. Open the contacts section of Outlook by clicking on the people icon in the bottom left hand corner of the screen
2. Right click on your "Contacts" folder and click properties
3. Go to permissions
4. Click "Add" and select the individual you would like to share the folder with
5. Choose their permission levels by selecting them from the list and choosing either "Reader" if you want them to be able to see the list but not edit it and "Editor" if you want them to be able to see the list and edit it.
6. Click "Apply" and then "OK". They should now have access to your contacts folder and lists inside