Lan connection between winXP and win7

Hello digit!

My uncle has ethernet connected to a desktop with winXP. He recently bought a laptop which has win7 installed. He wants to connect the laptop to the internet to. The fact is I have no idea how to set up a lan connection in winXP over a modem, recently learned doing so in win7. I want a guide to setting up the lan connection in winXP.

Thanks.