You get a wireless router, you connect your PC to it by cable, since it would be a waste of money to spend $100 on another wireless adaptor for the PC. If you have 2 PC's that are close, wire them both up, if you have 2 PC's that are far apart, use wireless for 1 and cable for the other. Use your laptop's wireless card.

Then you set up the router and it will work, you might want to change a few settings to just not anybody can connect to your network!