Share all contacts in a folder:

1. Go to the People tab.
2. On the toolbar, click the Folder tab.
3. Click on the Folder Permissions button.
4. Go to the General tab and make sure the correct folder is selected. 
5. Go to the Permissions tab.
6. Click Add, and add the user that you would like to access your contacts.
7. Change the user's permissions to the appropriate level.