Since the process of setting up a network is somewhat complex, there are several places where problems can occur. Make sure the printer software is compatible with the Mac. Some printer manufacturers don't make Mac versions of their software. Open the Extensions Manager control panel and make sure the printer software is enabled. Try turning everything off and start the printer up first, before the Mac.
Some printers require that they be turned on before the computers.
Reinstall the printer software and try again. Without the correct Control Panels and Extensions installed, your Mac won't even know the network is there. Since the Mac loads all its networking software during the startup process, you'll need to restart your Mac after installation. For a list of the required network files, check out the Required Mac Networking Software page. Without the presence of shared folder, your Mac doesn't know that you want to share files with anyone, so it won't make itself visible to the network.