When Connecting Two Or More Computers Together
Using A Cable Network, You Will Require Several Components -

Patch Cables - Used For Connecting To Network Components.
Network Routers - Used For Connecting To Internet And These
Normally Have Additional Ports Which Can Make A Switched Network.
Network Switches - Used For Connecting Several PC's.
PowerLine Adapters - Used For Networking Through Your Homes Power Lines.

5-Port Switch

8-Port Switch

PowerLine Network Adapters

Network Patch Cable

Network Patch Cable Ends