Jouw = your
Uw = your (polite form. Like the word "sur" in the Spanish sentence "¿Cuál es su nombre?" = "Wat is uw naam?")
About je/jij/jou, they all mean you. I know that people usually write "je" but "jij" is more correct (personnally, I always write "je"). As far as I know, the word "jou" is used for instance in combination with some words like "met" or "naast": hoe gaat het met jou? (how are you?) Ik ben het eens met jou (I agree with you). Hij zit naast jou (he's sitting next to you)
Anyway my answer is not the best you can get. A native speaker should better explain it than me.