Anything あなた want... journal entries, taking notes in class, doodling, 書く stories, songs, または poems, 書く things down that あなた don't want to forget, keep track of your お気に入り quotes, use it to make lists, make paper airplanes... the 一覧 goes on. :)
Maybe a diary, または maybe notes for school または for hobbies like if あなた write. または maybe あなた can use it to draw, that's what my cousin does. Just doodle with it. Use it to do your homework on. Anything あなた want!