Follow these steps..
1) Wait til she comes
2) Buy her a cake
3) Put "Prom?" On cake
4) Throw it at her
5) Ask her to prom

Why are you asking someone so far away in the first place. Isn't there someone closer you could ask. Sorry I just had to ask. Anyway if she has already said yes then you don't need to do anything else. What else can she say

IndianBoymodz wrote Me and this girl are going to prom together, and she lives in another state. I already bought her plane ticket and she said yeah already. Her birthday is coming up soon and i want to ask her in a better way. Any ideas?

Zesri wrote

IndianBoymodz wrote Me and this girl are going to prom together, and she lives in another state. I already bought her plane ticket and she said yeah already. Her birthday is coming up soon and i want to ask her in a better way. Any ideas?

Wait, you said you two are already going together, but you want to know how to ask her in a better way?

I'm confused.

He wants to do a prom proposal...
Honestly just you flying her out is enough. But do something special, maybe have a special dinner outside in your backyard, candle lit, homemade (or takeout... your choice there lmfao). You really don't need to go overboard, it's like valentines day. You give a girl 1 rose and that 1 rose has so much more meaning than a bouquet of roses.