Being somewhat general here, you should get a wireless router. Such as a
Airport Extreme Base Station or similar router. The Airport can handle up to 50 connections at once, which in most cases is a lot more than home users ever need. You'll then need to plug the network cable that comes from the broadband modem or other device into the Airport and then use the provided base station utility to set up the connection.
What I have here at home is an antenna that looks like a satellite dish. However it doesn't point at a satellite. It points at an antenna about three miles from my house which provides broadband service. The broadband modem is built right into the antenna, so the installer just ran a CAT5 cable from the antenna right to the back of our airport extreme. This company assigned us an IP address which I entered manually into the Airport configuration utility and then once that was done we were on line.