After setting up our WooCommerce Attribute Images plugin you can assign your first image to an attribute. So go to wp-admin > products > attributes. Then you can either create a new attribute or open an existing one. When opening an existing one, click on configure terms. On the bottom of the attribute settings you will find a new Option to set an attribute image.
So set an image, save and then you can go back to your product page to see the result.