The iMac is already connected to the internet via a wireless connection, but the network is set up to allow sharing between computers, etc...The other computers on the network are PCs. Is this the reason the Mac doesn't show them? Is there a way to set up the Mac to share on the network in the same way? Like printing to the office printer, viewing and saving files to other computers, etc.

Follow these steps to select the appropriate protocols for the kind of computer that will log onto your Mac:

1. In Sharing preferences, click the "Options..." button.
2. Select "Share files and folders using AFP" to enable the Apple Filing Protocol. Use this protocol to file share with other Macs.
3. Select "Share files and folders using FTP" to enable the File Transfer Protocol. Use this protocol to file share with UNIX and LINUX systems.
4. Select "Share files and folders using SMB" to enable the Server Message Block protocol and check the user accounts to enable for SMB. Use this protocol to file share with Microsoft Windows-based PCs.

Note: You will have to enter the user's password for a user account that you enable for SMB.

5. Once you have selected the desired networking protocols, click "Done" to complete the process.