Hi Endi, those images should point to a directory on your site where the plugin is installed. For example the first image should be accessible at:
If the images aren't accessible, then either there is a misconfiguration with your server/installation, or I made an assumption while writing the plugin which doesn't hold in your case.
Is your site online? I can try and take a look.
I think it would be easier to help you through a proper chat platform. Can you write to me on the Gitter forum for the NovemberGallery plugin? Here: https://gitter.im/november-gallery/community