You will have to have a router to make a wifi network if you only have a wired modem.
You can share a USB modem internet to other computers on the network by simply creating a wireless network with the comp where the modem is connected and then connecting the other computers to the network via the wireless network that you created.
For cable modem networking to work the cable modem will need to be connected to a network hub. This will allow all computers in the network to connect to the internet.
Router will use connecting to modem
central processing unit browser network processor network
A modem connects your computer to the Internet. A router takes the Internet signal and splits it up and distributes it to other computers on your network. There are two types of routers, wired and wireless. A wired modem router uses a cat5 cable to connect to the modem and to connect to each computer on the network. A wireless router uses wires to connect to the modem but connects to each computer on the network without wires.
A modem
Network interface card Router Modem Swich
You connect you PS3 to the Modem to allow you access to the PlayStation Network with either an ethernet cable or a WiFi connection with a wireless modem or router
modem
A router, modem, and an ISP.
a router or a modem