Make header have background image

I would like my header to be a background image instead of a solid color. How can I do this, so that my image is the background, but also so that my image is center and does not repeat?

Thank you in advance.

 

Hello,

Paste this code in Custom CSS
Appearance > Theme Option > Styling Option > Custom CSS

Code:

.header_container {
background: url(ENTER YOUR IMAGE ADDRESS HERE) no-repeat center center fixed;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}