To insert an image into a chapter:
Position your cursor where you want the image to appear.
Click on the picture icon in the toolbar.
Choose an image from the gallery or import a new one from your computer.
Customize the image using options such as caption, alignment, text wrapping, separate page, size adjustment, and links.
Click the green Upload Image button
You can learn more about the process in this tutorial: https://www.atticus.io/interior-book-images/