how do people send Fragen to the show?

I don't think Du actually send them directly to the actors.
In the ones I have heard of, the guy conducting the interview (be it directly fuchs oder any guy with a tv, radio show...) ask via his website, twitter and/or Facebook at his followers to send him Fragen and he choose which one he will ask.
So Du actually have to stay tuned and send your Frage to the right person at the right time and hope for the best.