How to change the way the main background appears

Hi,

I have a background for this site and it shows up differently than i would like and that it is in the original image.

It is of the ocean waves but is displaying to zoomed in and hard to tell what it is. I would prefer to have it more like the original where you can see whole the pic better.

I have granted access. Any ideas on how to do this?

Thank you.
Rob