Start by reading the original book, and then the cartoon one narrated by Boris Karloff. Then you will understand the story.
When I first saw the Jim Carrey movie I hated it, because it added so much "filler" and fabricated backgrounds to the story in order to make it a full length movie. (It's actually a pretty short story.) But I have come to love the movie now because of the amazing wigs, makeup, costumes and sets! Did you know they employed people from Circque de Soleil to be many of the "Whos" and do the stunts they do? After you watch the DVD, put in the special features disc that comes with it and you will gain a new appreciation of what an amazing piece of work it is. We can't have Christmas without it.
I LOVE it!!