Aerial posts?

  I'm new to all this and have only had one outing (in the van) this year. My other half has asked me to fit an aerial, not too sure about this. We have a small TV with built in DVD player, which I'd planned to use for entertainment. I see that some sites have a TV point on the EHU post. How does this work, do you need just a long coax lead, what plugs, how long, what sort of reception?? Questions, questions.