I need help with my vampire deck?

Well, Not really looking at the cards you have, I would recommend getting rid of the Child of Nights main board as well as getting rid of Sengir Vampire (terrible card) and adding more Vampire Nighthawks and Gatekeeper of Malakir (both are great utility cards). Also, 20 Swamps seems a bit low... you may want to boost that up to 22-24 and then if you can get your hands on a few Lashwrithe, those go great in monoblack, especially when you can attach one to a Vampire Nighthawk and start gaining life in a major way with him.