How to get a role in a horror movie?
How can a 14 year old girl get a horror movie role?
Tell the producers that you have practiced having a knife go through your back and are ready for the real thing. They'll gladly accept and may even pay you millions to get stabbed.
Audition. I don't understand the problem.
Go down to Hollywood and talk to someone that works in any of the production studios for a hook up...
Be on the lookout for auditions.