How can i get close to her?

So i have a crush on a girl in my class which is fairly popular but we are in the same friendgroupe and she also finds me funny when i make jokes but we never talk slonr and only when other people are around so what shall i do? I also meeting with her best friend( he allways has a big group of friends in his house) fairly often and sometimes we both are there and she said that im vrry friendly.