A typical router has one input Ethernet feed from the Modem (or can be a combination modem router) and has a number of output feeds that go to various computers connected to it. You hook up the cables and run the Local network setup if you want the computers to talk to each other. You have to deal with what is shared between and which computers have access and which do not.
If you intend to use the wireless features, you have to run the wireless setup also and may need drivers installed from a CD that came with it.
If you can find your router in a google search, it can translate the pages from Korean to English.