Changing background image

Hi all,

I’ve been asked to simply change the background image on a homepage. Not as simple as I had initially thought, I can’t seem to find a way to do it. It seems to be built into the theme of the site. When I search the current image’s URL it doesn’t turn up in the cPanel database other than in the image gallery index.

I’ve also tried finding it inside Editor, though it doesn’t turn up their either. Where am I going wrong?

Apologies if there’s a similar question floating around in here, if so I was unable to locate it.

Thanks,
Aaron

The page I need help with: [log in to see the link]