Hi
I would like to change the background image in the header which is on all pages accept the homepage. The image is some grey gradient, and in the code I couldn't find the location of the image as it gives me some strange long code where the path to the image should be..
How do I change the path to that image?

Thank you, regards

It is a base64 encoding so you can freely change the bg and still maintain the gradient.

All you need to do it override it in your custom.css file
.radialGradient { background-image: url(path/to/image.jpg); }

If you put the image in the template's folder (templates/businessone/images) then the CSS rule would be:
.radialGradient { background-image: url(../images/image.jpg); }