An image message enables you to display an image along with an optional link behind it to make it clickable. You have the option to enable this to open in a new tab or not.
To add an image you will need to first host the image somewhere external from OpenDialog; either on your website or in an Amazon S3 bucket, then paste in the URL to the 'Image Source' field. See the example below.
Message editor: Image message.
Saves Message: Always remember to hit 'Save Message' before closing or navigating away from the edit screen.