Copying another site graphic question

Hi,

On this site I would like to move it to GP, it's a basic site but notice in the parallax movement as you scroll down, the water in the screens of the computer pics, like phone and such. Notice how the screens are showing the background image which is part of the header image? which is part of the site's background?

In copying this over to GP easy to do? Is it a matter of making the header image be the background image?

Thanks,