how do I set up three iphones on home sharing

I just bought a new IMac and the salesperson told us of all the benefits of homesharing. There are three of us in the house (each with an Iphone), the IMac, and a Windows 7 laptop. I have home sharing turned on in all the computers and phones but I have no idea what to do know. Each phone is logged into home sharing by their individual Itunes account and the computers are logged in on homesharing on my Itunes account. I think I'm missing something simple, but I can't figure this out. Anybody know what I'm doing wrong?