When I saw a girl in the library, I was a little introverted about how to go up and talk.
Dare but cautious, thick-skinned ~ because you are introverted ~ I suggest you meet her more often in the library. After a few times, you both have to find each other's existence, create opportunities to see each other, and nod! This is a natural understanding! It's up to you to get to know each other later.