I'm working on a site for our clinic, here: www.markshoushadentistry.com

I am trying to change the background on the pages (not home page) from white to a textured image background. I've located using Inspect in Chrome the CSS is:

```
.site-content {
    background: #FFF;
}

```

But I can't seem to find where it is to change it. There is an option in customizer that changes the color of the background, but I'm trying to change the background to an image. 

Can anyone tell me where the code is to change the background color to an image?

Thanks so much in advance