Most Helpful Girl
I don't know how long your hair is so I am going to give you a few options:
For prom I would do an updo, maybe have some pieces hanging down and curled a bit :) You can curl your hair and then pin it up with some pretty clips. Like this: link
You can wear long dangling earrings with an updo for an even more dramatic effect. Even curling your hair, putting it in a pony and then using a pretty clip to clip it up, will look nice :) You can even add a headband or tiara to give it more glamour.
Or you could leave it down and just curl it or straighten it, push it back with a headband or pin it to the side with a beautiful flower pin. This works for short, long and medium hair link
I would suggest and updo though, just because it is the summer and it will get hot with you dancing and all. I know at my prom I had my hair curled and it was down, and I sweated so much my hair looked bad after :S So just a word of advice :P
Another option is a half updo. link
This will be lighter than having your hair all down and it looks nice for any event :) With this style you can also wear long dangling earrings, or even just simple studs, or one dramatic big necklace.
If you want to do an updo or a half updo or the ponytail idea and don't have long hair, you can also try a hairpiece :) Most accessory stores have them.
Hopefully this helps! I have had a lot of prom/formal event experience so if you have any more questions please don't hesitate to message me or comment :)