When you activate your theme, you will have a full width layout. However, this theme also includes a background option which lets you colourize it or you can use an image background. To show this, you can change your page layout to a boxed layout with a variety of sizing from full width, 1800px, 1600px, and then 1400px.
Full Width
Boxed 1800px
Boxed 1600px
Boxed 1400px
