On the rear of your cable modem, there will be two telephone jacks. Many cable companies will offer you up to two lines with different telephone numbers. They are smaller than the connectors for the internet and you can simply plug your telephone right into one of those jacks.
That's all there is to it unless you have two or more phones! The best part of this is that you can go to your local BOX store and buy a splitter that plugs into your modem and gives you two telephone connections.
The telephone connection is actually just two wires and if you are the slightest bit handy you can make a cable connection block and connect the two wires from the modem and the two wires from each telephone together. The limit is probably around five or six phones, depending on your modem.
Also you might get one of the nice portable home phones with several individual phone handsets and use one of them. They are nice because they are wireless and once the base unit is connected to your modem, no further wiring is necessary.