To put Trello Board on your Digital Signs.
Got to Trello.com on your browser, open the board,
Copy the board's URL Link from the address bar.
Go to app.optisigns.com.
Click Files/Assets, then click Apps
Then click Trello app
Paste the Trello Board URL in.
On your device, if your Trello Board is private, you will need to enter in username and password to log in.
You only need to do it once and set remember credential.
If you are using FireStick, you can connect up a Bluetooth keyboard, mouse to enter the User name and password. Here is a related article.