Mac OS X 10.5 Help
Creating account groups
Account groups are a type of account that consists of one or more other accounts, called members. When sharing files you can give access of files to a group, and all the accounts that are members of the group will have access to the files. You cannot physically log into a computer using a group account name like you can with most other accounts.
To create an account group:
If the preferences pane is locked, click the lock icon and enter an administrator name and password.
Click the Add (+) button, located below the list of accounts, to create a new account.
Select a Group from the New Account pop-up menu.
Enter a name for the group, and then click Create Group.
Select the checkboxes by the accounts to be members in the group.
You can manage the files and folders that group accounts have in Sharing preferences. The group will appear as one of the sharing users when you add a new user.