It is in fact a billboard which uses LED technology instead of printed vinyl to display a message.
Stick to one idea, and make it a simple bold statement. A simple ad will have greater retention.
Because of the brightness of LED displays it is most effective to use a dark background with light copy. Use high contrast for text and high resolution photographs.
Color Settings - RGB
Pixel Size - Confirm exact pixel matrix with your account manager.
Final Output - The actual file displayed will be a non-compressed 72 ppi jpeg at the Pixel Dimensions of the particular display in use.
Important: The pixel dimensions are critical to a successful posting - Each sign has a pixel count or matrix, based on the pixel pitch and the number of modules.
Use high quality photos which are correctly exposed and have good saturation of color. Professional stock photos are the best choice. Images which have good depth and accurate focus will translate well to the display. Bright images with very vivid colors are better than darker low contrast images.
It is best to work from the high res original in RGB and only down sample the image as the final step in working with the file.