How can I get a good part in a musical (High school) for my first audition?

I need tips on training (my voice and things I'll need) and stage presence, blah blah blah... This will be my first time auditioning for anything, let alone a HIGH SCHOOL level play...When school starts. And I can't help but be nervous. Also, will I get a good solo or duet of some sort if they like my voice, but I don't have any experience on my 'resume'? I have a lot of questions, I know. But I'm really nervous. I also would like to know what being in a play is like-even though hopefully I'll find out- and I'd like to know what the people supervising the whole project will want to see. :)
So I can be prepared, I guess.
Thanks :D
P.S., Are there any songs from different musicals I could possibly practice? Or...'numbers', I really don't know. But I'd love to be in this play, and also I'm auditioning with a friend.
I'm a fairly good singer. I've been singing for years. I pretty much practice every day. I'm the type of person that gets really nervous but does it for the fun anyway. (Sort of like riding roller coasters except I need talent, although one thing is similar: Guts.)) :D
Thanks again!!

Oh and the guy below me who said 'show some cleavage': I thought that was horrifically rude. Why would you say that to anyone? Don't be a pig. Let me guess, you're the agitating idiot who doesn't have any friends that are GIRLS.
This is my first time posting one of these questions, and I don't find your joke funny.
I hope other girls don't have to deal with your garbage...

For your audition:
Go all out! Ham it up. Act like you would if you were alone or being filmed for a movie. Sing your heart out. Virtually IGNORE those in the room (except whoever you're acting with). It's the once chance you have to show how good you are. A r茅sum茅 in HS isn't important. That comes later, much later.

What it's like:
It's a tough schedule between choreography (if you're doing a musical, which I'm assuming you are), blocking, vocal coaching, and rehearsals. But, it is a blast as you'll get to know your castmates really well and there's only one kind of bond like that. It's amazing. It's just like when you play a team sport. And performing is a blast! Especially when you have those bright spotlights because it lets you forget about the fourth wall (the audience) and just act/sing. You can't see anyone in the audience which, in my opinion, definitely helps with the nerves.

To practice:
Do loads of vocal warm-ups. I'm unsure of your range, but working on the songs listed below definitely do help and can also be used in auditions. As for acting, watch the taped version of the Broadway performance of Into the Woods. (For a musical comedy, you can act without the fourth wall. However, don't do this for anything but the musical comedy.)

If you're a soprano -
No One is Alone from Into the Woods
Will I Lose My Dignity from Rent (needs lots of control)
Castle on a Cloud from Les Mis
Wishing You Were Somehow Here Again from Phantom

Mezzo/Alto -
In His Eyes from Jekyll & Hyde
I'll Give My Life For You from Miss Saigon
When You're Good to Mama from Chicago
You're What You Own from Rent

The key is practice, practice, practice. Once you feel you're ready, audition. Also remember that there are no small parts only small actors. Good luck, I wish you the very best!!
P.S. You go girl!! I'm so with you on that guy's comment!!!!!

Umm well like you said you practice so if you sing on your own i expect you sound good. Now a lot of ppl dont have much experience and well everyone has to start from somewhere. Look all i could tell you is get a voice teacher. The voice teacher will then pick out a piece of music you can practice on and they will critique you. Now critisism is the thing that stands out to a performer after their performance and well when you audition you are gonna be critiqued so might as well learn to sing infront of a person who is giving you positive critisism and so that you could take their advice and improve your vocals. If you cant take the voice teachers critisism dont expect to be able to handle the judges judging your audition or a large crowd

Songs:
Phantom of the Opera - Phantom of the Opera
Colors of the Wind - Pocahontas
Enchanted Songs - Enchanted
A Whole New World - Aladdin
A Dream is a Wish your Heart Makes - Cinderella
Journey to the Past - Anastasia
Part of your world - The Little Mermaid

I would say these songs for beginners

Tips:
Drink Plenty of water
Practice, but don't over practice or you'll spoil your voice
When nervous, DON'T IMAGINE THEM IN THEIR UNDERWEAR IT WILL JUST MAKE YOU LAUGH OR WEIRD FACES!!!!! Just think that no one else is there or that they are your friends, but don't goof of.
Just Have Fun!

hope i helped