basic computer networking

You just use router etc data link, to use as connector between 3 computers. Then you can share using internet and share folder, files even use a single device share each other.

You need a router to connect the computers to connect the printers i don't know but for the computers i am shure.

I'm connecting 2 laptops using a wireless connection, one of them is connected to the internet(dial up) and the other one connects to the internet through the first one. Its called internet connection sharing and its a property of the Dial up connection in the advanced tab (windows XP). Also you can use the pc that is connected to the net as a proxy for the other two.

Of course you need a network controller which is connect to every of your pc. after you have done it. You must share you hardware so that the networked pc can see it.

If you want to connect your PC's you need to insert LAN card, its the simplest way to connect PC's. For any details on computer hardware and networking, you may check the site below, which provides notes on computer hardware and networking. http://hardwareandnetworking.org