Could I possibly convince you to sing rather than indistinguishable screaming EMO nonense? No? Damn.

Well I'll give you some pointers. Rather than using the vocal chords you use normally you'll want to try and use the "false" vocal chords. They are generally found lower down on the neck. It'll be hard to get used to using them at first since you're natural instinct is to use your normal vocal chords when making any sound. To practice it, try breathing out slowly whilst saying a single letter (It doesn't matter, but A or E will work best). Consciously push your throat down whilst your doing it. You'll feel the vibrations primarily in the bottom part of your neck rather than nearer the adam's apple. Those are the one's you should be using to make "screaming" noises. I wouldn't recommend using your normal vocal chords for this. While you'll be able to make a more acute sound, you'll inevitably end up doing damage since the vocal chords aren't mean to make such noises for prolonged periods of time, if at all.