Header color change?

Hi,

ALWAYS Make a backup of your site, before making any changes!!

1. Use FTP to backup the files.
2. Make sure to also backup your database.

http://codex.ww.wp.xz.cn/Backing_Up_Your_Database

3. Use a childtheme to make the changes in
   Suggestion: use the ‘one click childtheme plugin’.

Add the following code to style.css of your childtheme:

#masthead:before {
	/*background: url('images/background.jpg'); This blocks the brown image*/
	background-attachment: fixed;
	background-size: 400px auto;
	box-shadow: 1px 0 3px 0 rgba(0,0,0,.7);
	content: "";
	padding: 1.8em;
	position: fixed;
		top: 0;
		left: 0;
	text-align: center;
	z-index: -1;
	width: 316px;
	height: 100%;
	background-color:#9966cc; /*change the color-code to suit your needs*/
}

Check:
http://colorpicker.com
http://codex.ww.wp.xz.cn/Getting_Started_with_WordPress
http://codex.ww.wp.xz.cn/CSS
http://codex.ww.wp.xz.cn/Finding_Your_CSS_Styles
http://codex.ww.wp.xz.cn/FAQ_Troubleshooting
http://codex.ww.wp.xz.cn/Backing_Up_Your_Database