You can either share a private contact folder by right
clicking the folder, selecting properties, then the
permissions tab. Add the users that you want to see this
folder, select the "role" (permission level) that you want
them to have. You can also create a Shared contact folder
in the Public Folders list by going to File/New/Folder,
enter a folder name (I.e., Shared contacts), under 'Folder
Contains' select Contact Items, under 'Select where to
place the folder' select Public Folders, select OK. Once
you've create the public Contact Folder, right click it,
go to Properties, then the Permissions tab where you will
add users and assign permission levels to them.
I hope this helps you.
Thanks,
Efowler