Images are key for making your listing and its content stand out. The Single Image Box can be used to add images within your template like your company logo, banner, size charts, etc. It is designed to be responsive which means that the images you include in your template automatically resize depending on the screen size it is being viewed from.
To add a Single Image box, click the "Elements" tab and find the "Single Image box" widget from the list. Drag and drop the widget on the spot where you wish to place the icon. You can click the edit button to change the image by putting the image URL. See this article on how to add and get your image URL