labecs

I am using the Lifestyle theme for Wordpress, and I am a true beginner in everything code and design etc.
(http://www.yourpetsuniverse.com)
So far I've managed to use images as background and changing the headers, but...
I saw this website and it's also a Lifestyle theme, but... how can I get that effect of the image sticking out of the header and changing the whole background like that?

http://www.truemanhood.com/category/blog-2

Is it done with code? How do I prepare the picture that will stick out? Please, somebody tell me!