Cable broadband is one of several technologies available for connecting to the internet in Australia. It is an entirely different technology to ADSL and most of the NBN.
The technology relies on a network of hybrid fibre coaxial (HFC) cables being installed in a suburb. To get Cable either Telstra or Optus needs to have installed these cables in your neighbourhood sometime in the past.
If there is no cable in your area now it is unlikely that any company will install the technology and you will have to wait for the NBN to get fast broadband.
The easiest way to check if you can get Cable is to go to both the Telstra and Optus websites and run an address check.