It's simple to change your page background settings — as long as you don't confuse them with your site background settings. Here's the difference: the Site background surrounds the Page background.
|Page Background Settings|
|Width||Use the slider to increase or decrease the width of your page, or enter a dimension.|
|Height||Use the slider to increase or decrease the height of your page, or enter a dimension. You cannot create a page shorter than its content; you'll need to first move some of the content to another page.|
|Top position||Use the slider to increase or decrease the distance of your Web page from the top of the screen, or enter a dimension.|
|Color||Click the color picker, and then select the color you want to use.|
The change is applied to every page on your Website.