How to know a girl's birthday?

I gave her a birthday present from the first week, saying it was for you, because I don't know your birthday, so you should accept it whether it is right or not. The second week, the third week, it will be sent to her until she tells you. A gift doesn't have to be expensive, even if it's a bookmark made of leaves. Use a paragraph to explain the making process of this gift and your mood at that time, I think.