Most e-commerce and web site content management systems do not make life easy when it comes to editing images.
Adding a new product image is just one click making your thumb nail and also your main image, no imaging software is needed.
You also have the option to input other images if your product has different colours / styles.
You also have a dedicated image admin area where you can View, Upload, Delete images.
We do suggest you name your images and offer help in this area.