It's simple. Get a cable modem router like a Linksys and follow their instructions on how to setup.
I have one connected to a cable modem, now myHusband brought home another computer for his use. I wanted to know do I have to buy a router or is there a adaptor I can buy to put in my cable modem to connect both computers? I don't need them to communicate, I just want to be able to have both online at same time. Thank you!! Marie