This Plugin provide functions like post-thumbnails for categories and (own) custom taxonomys. Please visit the Author-URL for Documentation.
Going into the WordPress Administration (wp-admin) and search this Plugin. Here you can install the plugin easyest. Optionally you can download the Plugin as ZIP-Archive on the WordPress.org Site and upload it to your WordPress site.
No Problem! Contacting me, if you need a Plugin :-)
Please contact me, i will fix that shortly.