I wouldn't recommend trying to make a girl a wallflower. It's better to encourage friendships and a sense of belonging for everyone in the high school setting. Such negative actions can have a lasting impact on someone's self-esteem and social life.
I'm not sure specifically as it could vary a lot. But generally, it might be about the experiences of a wallflower, a shy student, in high school. Maybe it involves things like making friends, dealing with bullies, or falling in love for the first time.
I don't know for sure, but it could be the wallflower character themselves. Maybe there's also a popular student who befriends the wallflower or a teacher who helps them come out of their shell.
Well, start by being friendly and approachable. Try to strike up conversations with her about common interests and show genuine interest in what she has to say.