http://www.911tabs.com/link/?7214797

So how would I play this on the piano? O_O

That is just giving you the chords of the song. You are missing the melody. You can keep searching or try to transcribe the melody. You have at last the chords. :)

Is the melody really needed if you are going to sing with it?

Nop. If you are using the piano just as an accompaniment, the melody is not necessary needed in the piano. If that is what you mean. :)

Okay, so... I would play C Chord once than the other chords when it goes to that line or something?

You play then as you seem them

play each chord and you can even break them and play each root key to make the melody