do you have to write? I don't think there is any substantial difference between writing a letter and saying it in person-for a relationship as unfamiliar as yours, writing a letter and saying it in person are both abrupt, but "writing a letter" is not so embarrassing to do.

While it's Mid-Autumn Festival, send short message blessing, take the opportunity to chat, get to know each other first, and then you can talk after greeting when you walk on the road, and then you can borrow books from her, find opportunities to contact her, so that she won't feel unfamiliar with you, and then talk about learning together. Anyway, get acquainted first, and then find opportunities to invite her out to buy books or go out to play later (I don't know that your home is far away)

Besides, since she can borrow books from you, why can't you say hello when you meet her on the road? Say hello. It's normal and normal. Don't be so nervous that you don't even say hello.

write a letter to be a friend. Everyone knows that such a letter means more than just being a friend. I think it's better to say hello and send a blessing message than to write a letter as a friend, right?

Everything is difficult at the beginning, so take this step bravely! Good luck.