You need LAN crossover cable CAT5 (Category 5) rs.20 per meter. Buy according to both pc distance. RJ-45 connectors rs.10. If old pc then LAN card rs.450. Mostly new motherboard come with onboard ethernet. Connect both end of the cable to LAN port back of both computers.
First give both comouters different name and IP. Configure as follows
Right-click My Computer>Properties. Select Computer Name>Change>PC1. Work Group>WG (This name will be same in both)
Now go to Control Pane>Network Connections. Right-click on LAN connection>Properties>General>Internet Protocol(TCP/IP) Click,Properties and set values
Repeat same procedure in second pc with these changes
Restart both compuers. Now they are connected by LAN
You can view the pcs in My Network and ready to play multiplayer game