More screengrab action...this time from the Hitchcock film "Lifeboat".
Values - the arrangement of black, white and grey - are an esssential part of making a successful drawing (or frame of a movie). Values can be helpful in giving form to shapes so that they have depth. Values can help to organize the elements in your frame so that everything can read. They can be used to pull similar objects together or to seperate objects from each other.
Usually the things closest to the camera have the most contrast, and things further away have less contrast, due to atmospheric perspective - all the dust and/or water in the air gets between you and the thing you're looking at. So it's usually best to make the things in the foreground the darkest and have the values decrease on things furhter away from the camera.
If you really want to learn about values, looking at black and white movies can be very informative. I picked these for their great compositions as well.