Download the drivers (software) for your printer > Support - Black and White Multifunction Printers SCX-3405FW | Samsung Printers
If that's not the correct model, do a search on the Samsung website for the correct drivers for Mac OS X v10.7.
You have to first connect the printer to your home network, IE your router. Whether that is by WiFi or Wire, Ethernet cable, is up to how the printer connects to a network.
Once that is done and the printer is getting an IP address from the router then you can setup your Mac to print to it.