What approach should i take?

i met this girl who is a friend of a friend we all went on a road trip and the 1st day we got their she got drunk and I along with another guy took care of her but i did most of the work and we went out to the club and when she was dancing with another guy i got jealous but she gave me her number i texed from someone else phone and she called that phone she sounded polite and really welcoming in her tone and i texed her from someone else phone and she hasn't responded ( her phone must be off based on the last text mess. experience) she has a boyfriend but I am still interested what approach should i take to even have a future with her????????