How to apply a fullscreen background image

We are seeing more and more websites using fullscreen images - they look absolutely stunning. Naturally the Designer allows us to quite easily apply such images to our design as well.

First make sure you are logged in and upload the image file. Next, go to Content > Design to open the Designer.

Make sure Background is selected in the menu at the top of the Designer as shown in the image below. Now notice that two sections are outline below. We have the Background section which is used to apply either a background color (applied to all pages), and two additional options used to apply a background image to either all pages, or just the page currently visible to the designer.