To add images to your flow, drag n drop the image component from the 'Components' tab into your step:
Once dropped, a menu will open where you can drag n drop files, upload files or add in image URLs:
Once a file has been added, an image will appear on the right hand side:
Click on the image, and the image will be added into your flow!
Once the image is added, it can be resized, moved, duplicated and deleted.