You guess random words until you figure out what the song is, once you figure out the song you can fill it out with the rest of the lyrics. The one of these for each of the songs.
This is a great quiz but I recommend allowing more variations of certain words. For instance, instead of making the player guess "Ev'ry", allow them to write "Every". I think this would make the quiz much more accessible for many players. Also, I agree with the other comments, there definitely needs to be more time. Once you figure out the song you still need time to write all of the lyrics.