Did you publish your listing but don't see (all of) your images? One of the reasons could be that system did not finish processing the images before you navigated away.
Be patient! Uploaded Images will arrive in a queue, will be optimised for different screens and processed for thumbnails. It may take several minutes. Wait until you see the them disappear from queue to a appear as thumbnail below the queue:
You can move your images order with drag and drop and double click to select you main image.
Remember: once you have uploaded the images, you must remember to hit Save button so your images won't get lost!