mayonaise
You mail a letter to his address.
Public figures in the academic world can be contacted through their universities or, preferably, publishing houses. I suggest writing c/o Channel 4 or publishers Chatto and Windus, 20 Vauxhall Bridge...
David Fincher is 49 years old (birthdate: August 28, 1962).
Address: DreamWorks SKG, 1000 Flower Street, Glendale, California 91201; http://www.dreamworks.com.