Welcome to Styleforum!
The tie you are wearing is quite bold; I'd go with a white linen pocket square (note the linen part, nothing shiny!) To bring stuff down to earth a little.
I should also note that the CM section of Styleforum takes fits VERY seriously. As you're new and this is your prom (AKA you haven't been doing this very long) I'm going to pass on the critique, but if you post that in WAYWT, expect excoriation.
With that said, this is an AMAZING community; they're an absolute treasure trove of knowledge. I'm two years older than you, joined last year. I've learned more about style in that time than the rest of my life put together. I suggest hitting the Thrift Thread- most recommendations here are waaaay beyond our budget- that's where you get stuff on the cheap!