You have your main content without any sidebars for distraction free reading. This is great for a landing page where you want your viewer to be able to read your content without anything else on the sides.
In order to have your page follow this layout follow these instructions. When you are editing or creating a page in the backend of your site, on the right hand side there are options to choose from under the Page Attributes and under Templates there is a select dropdown list and from there you will select hte Page – No Sidebars option.