Is it "ok" to use the name of my school in a book i'm writing?

Sure, it’s legal, but when your old schoolmates read your book, you might not want them to wrongly see themselves in characters.

You can make anything happen to anyone anywhere in any work of fiction. If you are writing a history of your school, get your facts straight.

Get some permission(or legal permission in possible) from your school’s administrator/head master first. It’s required if you wants to publish a book for public.

I would avoid using any real names or places like stores or buildings and what not. I’ve seen it done in books like someone talks about pepsi and another lists some 80’s punk bands. the biggest concern is whether or not you’re violating patents or trademark laws. If you want to use your school, I would rename it but use the setting. In my novel, I used my hometown as a frame of reference for my writing but renamed the city.

Its legal, but not smart. Not smart at all.

PUBLISHER’S NOTE
This is a work of fiction. Names, characters, places, and incidents are either the product of the author’s imagination or are used fictitiously, and any resemblance to actual persons, living or dead, events, or locales is entirely coincidental.

Now you’re good.

It’s so easy just to make up a name for a fictional school.

Just do what @Haleth said and call it ‘Hell’s Cesspool High School, Generic City, America.” I’m sure it will describe the original school quite well.

Roman à clef