How to change the white background color on twenty thirteen theme

== == == change white txt-area

.hentry {
	background: #99cc66;

/*apple-green; change as required*/
}`

== == == change white background site

body{
   background:#ff0000;/*red; change as required*/
}

== == == use background-image

body{
   background-image:url('../uploads/backgroundphoto.png');
}

Make sure to include the correct and complete path to the image.
Image doesn’t show? check the path!

>> >> >>
If your theme has an option to customize the CSS like a ‘custom css’-TAB, place the above code there.
Is such a feature missing from your theme? See the instructions below.
Add the above code to the `style.css’ of your CHILDtheme:

You don’t have a childtheme yet?

1. Install and activate ‘one click childtheme plugin
2. create the childtheme
3. Dashboard > appearance > Themes > activate the childtheme
4. Make the changes in the CHILDtheme!
– copy php files / css-file(s) of the original theme [as required] to the childtheme directory and edit them as required.

Thanks so much for your very detailed response!
The second piece of code is the code that is my solution.
Cheers!