Go to your local Antenna supplier and buy a cable 'toner'. It is about $10 - you connect it to either end of the cable and you will hear a tone when you get the right cable. You can figure out all of your cables in an hour.
Go to the initial setup page for your TV. You have to turn the co-ax on and perform a scan. All TVs sold in the US and Canada MUST have a tuner built-in.
Did you try speaking to the store where you bought it?