The following code is used on the WP-Prosperity demo site to create the Wide Page Example 3 Layout, shown here.
You’ll want to create a new Page, select the “Wide Page” template from the drop-down list that appears in the Page Attributes metabox. Then you can paste the following blocks of code into the content editor field. Change as you like. For more info on the Wide Content shortcode, see the bottom of the Shortcode Guide here.
Important: when you paste in the code below, be sure to use the Text editor rather than the Visual editor (click thumbnail to right).