Full width/height header technique?

So you all are WPMU dev experts so I will try my question here. First of all, I purchased a theme form somewhere else, but I will try and see if you can answer here.

I love the layout of this demo, http://demo.qodeinteractive.com/bridge43// however, I am not sure how they did this. The current site, I would like to have a blue strip that superimposes over the big image in the background of the header. On top of that blue strip, I would like the logo and the navigation bar.

I am using the LayerSlider plugin for the homepage. Any suggestions you can offer at this point will help.