What to wear to a foundraiser?

I am a teenager, and my family is having a foundraiser for cancer. But this foundraiser is in the form of a dance, my fam. is going to be their but my friends too and a boy i like. I know CRAZY right! But idk what to wear. i want to wear a dress so could u please help me in that. i don't want anything too showy and if you could pick out some accesories and shoes that would be great too.