Help with this song i have to learn!?

I don't know how much this will help you for monday, but in the long run it does help. Take a deep breath, and basically say "aaaahhhh" or "ooooohhhh" trying to keep the same exact pitch until you run out of breath. "completely out of breath" doing this often, should help you to take bigger breaths which will help push more sound out from your diaphram. and also help in holding pitch. hope it helps.