Well, without being a negatice nancy, I think that you should try to get it published first. Ideas that are books for are so much more likely to get made into a film. Then you can seek out a screenwriter and give them to rights to make the film (or, if your book does well... they might pay YOU for the rights).
OR...? Have you thought about turning it into a screenplay yourself? If it already reads like a movie, perhaps you already have the key movie elements. A little formatting here and there, maybe post some pages here... we could help you through the process. Again though, it still is more likely to be made into a movie if you get the manuscript published or presented in someway before the screenplay.
I can't emphasize it enough. Lots of screenplays don't get made, just like books don't get published. What often happens is that a screenplay is used to represent the quality of the writer's work (a calling card, if you may) and then a production company gets them to write an idea that they already have been working on.
Maybe you could post some of your novel here to get some tips, or make some friends of some peeps that have found agents and publishers. Stick around, make friends. You'll get pointed in the right direction.
