How to connect two or more computers through lan

What are you attempting to do ?
The more details you give the better we are able to assist your issue.

What hardware do you already have? What operating systems are on each computer? Are you looking to share an Internet connection, send files back and forth, share a printer? As Curlyben mentioned, we need more details in order to help you.

Without knowing more, the best I can really say is to connect both computers to a router.