So I'm in grade 9 I've met this girl who is breathtakingly gorgeous and I've smiled at her I've gave her clues that I like her but she just doesn't notice. Others in the class have though and I'm afraid that someone will slip out and tell her and then I'd be ruined there's a semi formal dance coming up what should I do?

Ask her to the dance?

You could start by ​talking to her.

Open your mouth, make words come out, and see where it goes. Unless you are Brad Pitt or Zac Ephron you will get no's. And honestly they probably did as well. But you never get anywhere unless you speak so do it.

Well if someone else tells her you like her at least she will know. You can't get her to like you but if you talk to her she will know you're there.

How can I get this girl to like me

I always feel obliged to jump on that whenever I see it. You don't 'get' people to like you. Be yourself and friendly and nice and give compliments and HOPE they like you.
Good luck.
Yes, it's work, and there's a high failure rate, and that's life!

Keep perspective. You are a high school freshman and it will not likely be life changing if this one girl likes you or not. There will be many gorgeous girls, so relax. Try to get to know her and see if she likes you, but confidence comes from knowing every guy gets shot down. The guys who succeed are gracious about it if it happens, like, "you can't blame a guy for trying - you are one of the nicest girls in our grade". Then you wait five minutes and notice another cute girl and try again.

If you get razzed by the guys over asking her, own it. Like if they say, "John got shut down by Anna", you just say. "Yeah - brutal, but I had to ask her - she's really cute. No risk, no reward". If someone teases you that the girl is out of your league or somethibg, have a sense of humor about it. A guy friend of mine got that kind of teasing when we were in school and I still remember him with a big smile, saying to the other guys, "gentlemen - we all must strive to date girls who are out of our league...that's how we get into a better league!" In other words, keep a sense of humor and know before you ask any girl out that there is nothing to lose. If not her, it will be someone else.

To one the door, Try just saying "hi". When you see her in the hall, just say, "hi, Kate (or whatever her name is). You look nice today." If she says hi back, and seems friendly about it, try talking to her next time you have a chance. You don't have to be Mr. Slick. Just be normal - like if a test is coming up, you can talk about that. If she seems to like talking to you, you can more confidently ask her to the dance. If she brushes you off, maybe don't ask her.

Guess what, who cares what others see, most likely no one saw anything, but to you, at this age it seems like the world will end.

My son, also high school freshmen, had his first girlfriend, his entire life started being effected by her calling or not calling. They recently broke up, and he discovered there is more than one high school girl in the city.

You ask her out, and do it soon, before someone else does.

If she says no, you ask someone else out, and get a date and have a nice time.