Welcome on board!
If you're looking to open your shop and start selling your products on Sellix, we suggest you check our Help Docs and the "Get Started" section. It contains all the information you need in order to establish a successful business on our platform.
Regarding your question, you can enter pictures inside a product description by clicking the small image icon, as seen in the screenshot below:
We suggest uploading your images on Imgur, which is a free image-sharing platform. Enter your image as shown here: (https://i.imgur.com/yourimage.png) Also, please do not copy the page URL when uploading on Imgur. Right-click on the image and then copy the image URL to the paste.