How to change out link in top menu to an image?

Currently woocommerce added a cart link to the main top nav menu. I would like to replace that link with an image of a shopping cart. How do I do that?

I’ve tried using this code but it doesn’t work.

li#menu-item-189 a {
  display: block;
  background-image:url('http://fetgraphics.com/wp-content/themes/childofx/images/shopping-c...);
  background-repeat: no-repeat;
  width: 35px;
  height: 32px;
  text-indent: -9000px;
}