Thread: Set header image full width as in Demo

Set header image full width as in Demo

How do I get the header image like in your demo content to display right across the page? I have seen that the demo uses the guy on the train station image at 1920x1251px. But all images I try to upload just sit in the middle of the screen.
http://www.mediation.directory/ I have a comp image I am playing about with which is 1920x1408 but still cannot get that to fill the whole of the grey background area.
What Im I missing here please?
David