Authors out there?? Can you help me?

I love to read. Im the type of person that, even if she had a lot of homework, Id still be reading my fiction books. Even if I try to stop and do something else, my mind still goes back to whatever book Im in the middle of reading. I guess you could say Im obssessed. Right now, like everybody else, Im going through a vampire faze. LOL.. anyways... Im trying to write a book right now. My problem though, is Im really bad at dialogue. I have all these great ideas for my book, but when I try to right it down, my dialogue is BORING. I really love books with funny/witty characters, so I want that for my book. Can you guys give me some advice on how to make the dialogues better?