Valerie - when you add your photos - you need to add a link to the photo as well as a link to the listing. If you go to 7th icon across the top of this page (when you reply to a thread) it looks like and upward arrow on a horizontal line.
Then tick the circle that says “from the web” - add a link to your image there (you can get your image link by hovering over your image and then copying the image address)
Then at the bottom right of that page - it says “Show more” - press that and then add the link to your item as usual.
Hope I’ve explained it OK x