1. Open System Preferences>Sharing (let's call this machine 'computer 1').
2. Give the computer a name in the field at the top.
3. In the list on the left, click the checkbox for 'File sharing' (or 'Personal file sharing').
4. If there is a list of 'Shared Folders' (Leopard/Snow Leopard) you should see the Public Folder listed. (It's possible to share any folder by dragging it into the list).
5. Click the 'Start' button (Tiger); in Leopard/Snow Leopard check the File Sharing: on radio button is on.
6. You must repeat this process (1-6) with every other computer on the network.
7. In the Sharing pane of the machine you want to connect to ('computer 2') you will see, below the computer name the message 'Other computers on your local subnet can connect to your computer at afp://(IP number) or computername.local'. Make a note of this.
8. Now in the Finder menubar, choose Go then 'Network'. You will see a list of connected computers: double-click on computer 2; in the window which opens (right) you will see a list of the users, from which you can only select the Drop Box; to log in to your account click the 'Connect As...' button at top right.
9. The pane which opens (below) is also accessible from the 'Connect to server' window of the 'computer 1' - in the top field, 'Server address') type
afp://computername.local (from computer 2) and hit the 'Connect' button .
10.Enter your username and password. The icon for your account on computer 2 should mount on the desktop. You cannot access other people's accounts except for the Public Folder, the Drop Box and any folders they have designated as shared.
11. Make an alias of the icon for computer 2 and put it somewhere convenient. Now you can double-click it to make connection easy in future.
12. You can eject computer 2 like any disk: drag to the trash or highlight and command-e.