Category Image plugin does not show image in theme category archive page.....

I am using the following plugin:
which enables an imageto be uploaded for a category (posts category) on the category archive page. The plugin allows me to upload an image, but the archive category page does not display it. The notes say that some coding needs to be done if it does not show up. Could you tell me in which theme file (child file) and what code to put to get the image to be seen?
Thank you,