There are several things to look for in this matter. You could buy a hub and some more cables and connect the hub to the modem and to the pc's in question ( but this can lead to some problems). Your best bet that i think about it is to buy a router and hook all the pc's to that. that should be what you are looking for.

The cable to connect 2 PCs directly is called a "crossover" cable. All modern ethernet cables are UTP - unshielded twisted pairs.

But the solution to your problem depends on how your PC is currently connected to the Internet. If you're using a DSL or cable modem wired directly to your PC, then you probably don't have an additional network port to connect to the laptop. If you're already using a router, then you can connect the laptop to the router, too.