Hallelujah....

Recently, I heard the song Hallelujah by Rufus Wainwright....and I've heard the word numerous times....but I don't know what exactly it means.. I want to write a poem around it....but if I don't know anything about it, I cant. So please enlighten me and tell me everything ya guys know :) And, and, what do people mean when they say Amen?

EDIT: PL MOVE THIS TO MESSAGE FORUM

Ah thank you
and im sorry i posted this thread here....please move this to members message forum..srry!

Amen actually translates as "and so be it" xx