Computer techs, how do you add another computer(in thesame house), I

[morrismartha@ymailecom]

have att gateway and my nephews go a? computer, and what do they need to get on internet, need to know exactly, Im computer stupid, I think they need a wireless adapter, but will that get their computer on the internet(I'm using the phone line with no voice service, do they need the phone line connected to their comp too and will the wireless adapter recognize my gateway, pls help