The photo and description areas of the property are items that will be used mostly in upcoming features. The photos will be shown as thumbnails by property, be selectable/usable in email templates and used in our upcoming Hosted Sites feature (owner websites).
There are some beta features that a limited group of users are using already that use photos and descriptions, but most users will not see those features yet.
In order to use images in email templates, right now, you have to edit the HTML of the template directly using the HTML button on the editor. If you need help with that, send a message to help@ and we'll help you configure it.