Theres this girl that i like very much but i heard shes gona ask a guy to sadies which is in march what do ido

She knows i like her and its really hard for me to talk with her seeing as shes always surrounded by other girls, I dont want to rush things but i really dont want to see this happen, ive been wanted to ask her out but i dont know where to or how.. were sophmores in highschool thanks