Using C to output a key on a web page

Is there any way I can use ANSI C to output words onto a web page? Or if I'm completely off, what language (or script) is used to do this sort of stuff?

I wanna try this since I just found a website (virtualpiano), and now I want to make some kind of programming that can read out the "notes" and play it on the virtual piano.

Thanks a bunch!