I just need an opinion

Ok so im 15 years old ........ i recently got this really pretty girls number and we've chatted a bit on social media ........ the first problem is i dont know what to do next and ive never had a girlfriend before.......... and the last proplem is im 15 and shes 16, everybody says that younger girls can go for older guys but not the other way around ....... so what should i do next and do you think it can work