Find a gadget renderable object in the catalog. Here's a few:

Jumbotron
Wall mounted screen

 

You can find more by searching the catalog for "gadget"

Click the "Add to My Inventory" button

Click on a room's icon from the room list to visit the room

    Note: If the room you entered doesn't allow you to place or move furniture, you should find a different room or make your own.

Click the add furniture button


Click on the Gadget Renderable object you found in the catalog and select "Add to room"


Activate the move tool and position your object


With the move tool activated, Right Click on your object


Select the Edit tab

Select Gadget Options

Configure your Gadget options and click OK