Dvd Vcr Combo For Basic Cable TV Tuner/comp Hookup Questions?

TV tuner/comp hookup questions? - dvd vcr combo for basic cable

Ok I'm totally confused. I have this online TV tuner for my model:

http://www.toshibadirect.com/td/b2c/adet.to?seg=HHO&poid=420773

I prefer just what in the draft, but what I do now, how to detect a signal from my cable? It also allowed me to watch / I do not know what cable channel Boomerang and SOAPnet? We Metrocast basic cable is not shit with our combo DVD / VCR via a cable or anything. Just as the tuner for cable access? Im so totally confused!