How shuld I do frndship wid a girl I like?

Im a 16 yrs old boy. I like a simple & cute girl in my tuitions.I wanna make her my frnd. But da problem is shes always wid her frndzzz. I have talked to her many times when I find her alone. She also talks to me smiling & nicely & talks abut evrythng on wich I discuss or ask her. But its very rare that shes alone. I cant keep waiting for her frnds to be absent for tuitions to talk to her. Whnever her frnds r arund she just talks to thm. Always its me who has to start talking to her whnever shes alone. I want her to b my frnd & want her to give some more importance to than her frnds. Also I want thati not always me who starts the talk but herself also.. & I also have the fear that talking to her in front of her frnds might give her ofher frnds indication that I like her. They might tease her or make fun of me or make her against me. So what to do??/ plzzz suggest ideas how to solve all of these problems (consider the fact im 17yrs height 5”9 & wgt:80 kgs(5kgs more that a normal) & have pimples on face which im not able to cure. Tell fast as I have just 4 months to make her my frnd aftr that shes Levin tution for next seession. Iwanna make her as a gud frnd in thesee 2 weeks only. Plzz help me seriously!!& plz u dont make fun of mine)