I don't think he means an Outlook public folder.
On your PDC, create a folder, call it 'public folder 1' or whatever. Right click on the folder, select sharing and click the share as button. Give it a name, like public or some 1 word name (to make it simple). Leave the share permissions as is. Then right click on the folder again, go to security, and set the rights as follows:
Everyone: read
Author owner: full control
yourself (if you're not an admin): full control
Domain Admins : full control.
Now you have a share to map to.
Go to the netlogon folder on your pdc - C:\WINNT\system32\Repl\Import\Scripts
create a batch file called public.bat
in the bat file, put in
net use p: \\servername\public
p is the drive letter
server name is the name of your pdc
public is the name of the share you created - not the folder name
then go to user manager for domains, and for all the users you want to use this script, click on them, click profile and for the logon script put in public.bat
to do different departments, use the same logic, just name the folders after departments and share them with names like HR, ACCT, IT, etc. then create a different bat file for each department (unless you want to learn kix or pearl).
TO do depts also create a global group in user mgr called hr, it, etc, and then when you set security on the folder, instead of everyone - full control, select hr- full control.