This code, for the sake of the example, assumes that the image is blockquote.png, and the image is a 20 by 20 image, change for your own needs.
blockquote {
background:url(blockquote.png) scroll no-repeat 0 0;
padding:10px 10px 10px 15px;
}
You’ll probably have to fiddle around with the padding values, depending on the image you use.