Adding banner above header on Coraline

Hi, im working on https://www.hairtryer.com/ and I am trying to insert a simple banner image at the very top of the page above my custom header and above the navigation.

I thought there would be a plugin that let me do this easily but none of them seem to do this – just create options for widgets which doesnt do what I need.

I am happy just to add the image as a hack but need to be able to serve banners… can anyone help please?

C