how to change background color in header of 2012

Whats is 2012?

BTW Use inspect element tool to change color by changing CSS.

Sorry, I was asking about theme Twenty Twelve. I think I figured out something. What would be your thoughts to change just the header section of the site to #c6f1a1? I’ve tried to locate this section using Developer Tools on Google and making changes to the style sheet and haven’t had much success.

Paste this in your child theme style.css file and save it should change whole header background. And if you are not using Child theme then use Custom CSS plugin, so that while you will update theme, you wont lose any modification.

.site-header {
background: #c6f1a1;
}