Where in the css do I change the footer background color?

Thanks.

Add this code to your css/custom.css

.footer-lr-outer {
background: #FF0000;
}

www.joomlaplates.com/template-customizing
We are committed to help you with any type of support query, however we can't provide extensive help in terms of customizations. In general customizations may look simple but you will require solid knowledge of web technologies and programming skills to do them or hire a professional who can do it for you.