[Plugin: Random Image Block] Adding images to a category

I’m missing something here. How do I ass a category to an image (or add an image to a category)

I’ve installed the plug in, I’ve got a category called “postit notes” but I can’t figure out how to link the images that I want to display to that category.

In fact – I can’t get the plugin to display anything – not even the widget title and even if I don’t select a category, no images are shown. What am I doing wrong?

The images have been uploaded into Media Library

Cheers

https://www.ads-software.com/extend/plugins/random-image-block/