A beginner here... Here's the story: my guitar teacher makes a gig every summer with all his students. Most of the songs are instrumental, but he adds 2-3 songs with lyrics too. The problem is, we're without singers this year, and he asked me to try singing since (he says) I'm good at English...
I have to sing The House of The Rising Sun, but I can't reach the high notes, example:

My mother was a tailor
She sewed my new bluejeans
My father was a gamblin' man
Down in New Orleans

I just can't reach the high notes, also while trying to do it the volume of my voice goes down. Should I try to scream? When I try to scream I'm afraid of doing it.
Run towards the light exposing your soul.
Don't scream, it'll ruin your voice. If haven't really sang before, you can get to those higher notes with some practice.
If you can't reach the high notes then you can't reach the high notes.. You can only go so high man, have your teacher change the key of the song so its manageable for you.. The best vocalists in the world will face this problem and they handle it by doing as such. Make the song fit your range, don't try to stretch your range to fit the song, you'll only frustrate yourself and waste your time.
Zeppelin Addict +1

Eric Burdon was a great singer. He makes it look and sound easy, but those notes are up there.

Could I get some more talent in the monitors, please?

I know it sounds crazy, but try to learn to inhale your voice. www.thebelcantotechnique.com

Chris is the king of relating music things to other objects in real life.