When you set the site properties and clicked OK you were taken to what is called Plan view. There is a Home page at the top and a Master Page at the bottom of the window. I only needed one page. To get to Design View I double clicked the Home page which opened the interface.
On the left are a few basic tools and on the right are a variety of panels used to manipulate the content on the page. Along the top are the properties, which can be applied to the page, or anything selected on the page.
In this case, I wanted to have a black background. To accomplish this I click on the Browser Fill colour chip and chose black from the Colour Picker.