Comment Background Image

I know it’s simple CSS, but for the live of me I can’t figure out how to add a background image to my comment form. I want to replace the “white space” with a pre-made image. If you have any questions, feel free to reply.

Here’s my CSS File:
http://pandandapd.com/wp-content/themes/shades-of-blue/style.css

Here’s the code I’ve been trying:

#comment {
        background:image:url('wp-content/themes/shades-of-blue/images/comment_thanks.png ')
	color: #333333;
	font-size: 12px;
	font-family: Arial, Tahoma, Verdana;
	margin: 5px 0px 5px 0px;
	padding: 4px;
	border: 1px solid #E6E6E6;
	}

Thank You, please help!