Sharing of Desktop

Our enterprise has purchased a new stand-alone Mac (LionOS) and we need to understand sharing.

As deployed this Mac is not connected to a file server or the internet, has one account (the Admin account no less) which all users log onto to access the desktop. The desktop has 20 or so files and folders which five or six users share or collaborate on.

I need to make individual accounts for the five or six users, at the appropriate user level (i.e., regular users, not Admins) and access to the 20 or so files and folders on the desktop.

I’ve figured out how to make the accounts but need to know the best way to give access to the files and folders on the desktop.

Any ideas???