Christmas Sing-Along

So....I guess I'm singing at the Music Assembly my school is organizing for the last day of school. Totally not my suggestion. Our music teacher was asking around for volunteers to lead the sing-along, and lo and behold, my friends forced my hand way up in the air.
And then the teacher said, "Of course! scribbles! You must sing! You're good!"

...okay, so maybe this was my fault for choosing to sing at another assembly last year for the student council elections (very embarrassing, by the way).

But still. I've just taken a glance through the songs the rest of the class chose to have us perform, and I have no idea how to sing some of the songs on that list. I should have paid attention...but I was chatting with friends, and didn't even know we were supposed to be talking about the sing-along! So now I have to sing some sort of rock song...and I have no idea how it goes.

My friends just don't understand when I say NO, I'M NOT GOOD. I don't think my voice fits in with other peoples'...
HELP. We're practicing on Wednesday in-class, so...wish me luck!

Bizz,
scribbles