Scroll down to the "Add Content" page to find the Look & Feel section.
Click on the Digital Signage tab and click Add Digital Signage Layout link.
Choose one of the templates compatible with Digital Signage.
* For Retailers Tab: Image + Simple Description
* For Retailers Tab: Image + Description
* Other Tab: Fullscreen Image
* Other Tab: Fullscreen Video
Fill in all data that should be displayed, exactly as you have done it for a regular content. For example upload a Product Image (PNG or JPG), provide Product Title and Price.
After saving your content assign it to a Digital Signage Campaign.