Changing the Site Layout
Change your Site Layout from the Theme Options interface
You can easily change the Site Layout of your Blog by going to Appearance -> Theme Options -> General Settings -> Site Layout.
Possible options are: Wide, Extra Wide and Boxed.
The Boxed layout is useful if you want to set a background image for your entire site. To do that first go to Appearance -> Theme Options -> Site Layout and change it to Boxed.
Your site will now look like this – Boxed layout with a 960px container.
We can also change the size of the container – the actual space of your content area – from 960px to 1160px by using the Boxed Layout width. Change that value to 1160px and head on to Theme Options -> Basic Design.
Here we can set a Background Image that will appear on all our pages and posts.
Use the Outer Background option to upload and select a background image.
Try using a high quality image, but make sure you optimize it first. A recommended size would be: 1900×900 px since we want the image to cover the entire space of the browser window.
We also want the image to use the entire space, so we must also enable the Fullscreen Background option. Additionally you can use the Enable Parallax option to have a nice parallax effect when scrolling up and down your pages.
If you want to have a spacing above and below your actual site, use the Margin Top/Bottom option.