I would definately start with the first book, Twilight. I myself liked the movie. But like any book to film adaptation, the movie's never as good as the book. But I'm forwarning you, if you didn't enjoy the movie, there's a slight chance you might not like the books. Although I was annoyed with the plot screw ups, and absence and/or rushed (IMHO) pivital scenes, the movie still captures the heart of the book.