Big game tommorow!help...please read and say sumthing!

so im 14 in high school.
and tommorow we play a team that surpirzed ervery one with pullin the upset agaisnt one of the best high schools in the bay area.
im pitching tommorows game.
and my brother tells me if i pull out the win tommorow im goin to shock everyone too.
thats exactly what i want to do.
how do i get mentally prepared for this big game??
what should i do in terms of pitching???
how do i keep myself relaxed and SURPRISE THE CITY WITH THIS WIN???

Don’t concern yourself with things you have no control over. You have no control over whether others will be surprised. And that’s not what your focus should be. You should be focused on hitting your spots and getting batters out. Try to help your team win - not surprise everyone.

Mickey Rivers, a great centerfielder for the Yankees, once made this wise observation: “Ain’t no use worryin’ about things you have no control over, because if you have no control over them, ain’t no use worryin’. And ain’t no use worryin’ about things you have control over, because if you have control over them ain’t no use worryin’.” He was right. There are some things we can’t do anything about—forget them. And there are things we can do something about. Go after them.
You say you’re about to pitch a big game, and you have butterflies. All pitchers do to some extent. But remember one thing, and it’s probably the biggest thing imaginable: TRUST YOUR STUFF! Figure out what your best pitch is, and what your next best pitch is—and go with them. Move the ball around—high, low, inside, outside, and change speeds. And throw strikes. And the most important thing of all—relax, don’t worry about this or that, just concentrate on how you’re going to pitch to the batter—AND HOW YOU’LL GET HIM OUT.