Build A Medium Network And Connect It To The Internet?

I need to build a medium network and connect it to the internet MORE DETALIS; what are the hardware requiremnet i need to build this network?? i need to monitor and control every thing in this network. it should be like this(one ADSL line with high speed connection coming from my ISP-(internet service provider)++ a room to put all the equipment and decives use in the network=routers,modem,servers,cables and so on= ++ then from this room or place i divide the one line coming to sub-netwrks--in my case about 6 subnetworks-- then spread all the cables and so on, to each department or division