What do I have to do to become the valedictorian? 
It's most often the person with the highest GPA.
Interesting. How do I get that?
You'd have to get higher grades than everyone else in your graduating class. The title actually refers to the speech given at graduation, though. 
Ah, I am starting to get it now. What is the speech usually about?
It's a farewell address to the graduating students.