You can add images on products using the Images panel located on the Property column on the right handside of the interface.
A few options are available.
1- Click on the icon on the toolbar, to then drag/drop the image or to browse to select yor images and upload with icon
2- Drag/drop images to add in the bottom panel
3- Scan the QR code to add an image present on your smartphone, or if you want to take a live picture to upload. More detailed information on this option in the article mentioned below.
You can of course add multiple images to the same product in just one step, and even add the same image(s) to multiple products at once, simply by selecting the concerned products before the image upload.