Whoa guys:
CABLE TV wasn't mentioned, but I'll include it.
A coaxial cable is a 75 ohm cable for TV. The ends are usually an "F" connector. The female connector basically looks like threads with a small hole. The male has a piece of wire sticking out of something with female threads.
You can get a device that takes composite video (the RCA jacks and converts this to NTSC video). The old standard. They were availabe for about $20 without cables.
What I am concerned about is what the cable system is using. Compatability may not exist anymore.
With High definition, the standard is now something like QAM or something like that for high definition. Before you had to select broadcast or CABLE on the TV otherwise you could not get past channel 6.
If you don't have a QAM tuner, you may either need that device or have to rent a cable box from the cable provider.
The question is: What kind of format is the signal on the coax that you are trying to connect?