Can I change the background of one page to an image?

We’re using the Twenty Fifteen theme.

I want to change the background of one or two pages and use a jpeg image. Can I do that on just a few pages? I don’t want to interfere with the theme. This is a new product that will one day have it’s own site, but for now I need to keep it within our corporate site.

Also, I’m not a newbie but def not a pro. We’re a small business and I was just blessed to be named the one responsible for maintaining the site!