Make the menu/image a header?

Hi,

I am trying to get a similar look to the demo shots however my pages are starting up next to the menu rather than below it. Effectively making the menu a sidebar which isn’t what I want. I want the menu & photo at the top, and the page below.

I assume the pictures shown on the demo involve a widget in a footer sidebar but that’s where I want my pages to go. The image with menu overlay being at the top and approx. half screen height or less.

Is this possible?

Many thanks
Garry