Need help still? If so I can help.
Desu ne is something you want to tell them that you felt right or after the question you ask (with someone Same age, really friendly with ỏ ưith the person is younger than you)
And Desu ka? Is the word like "right?" Is the Question too. Usually they use to the person you not really friend or the person older than you (formal)
If you walk outside your door and look up you'll see that the sky is what's up. It made me put more than "the sky." But there ya go. That is what's up.
Is there a book or something