If the printer has a network port, then plug it into your router and install on each machine.
If the printer doesn't have a network port, then you would either need to buy a print server, or a router that has a print server built in (check
here for a list of suitable products at Memex). Then you would install the printer on each machine as in step one.
The other option is to plug it into one computer (probably your desktop) and share it with your network, and then install it on each computer by connecting to the printer share. The downside being that this computer would need to be on at the time when you wanted to print.