Hello.  I am new to the forum and re-introducing myself to model trains (I had an O27-gague set in the 1980s and my father has an O-gague set from the 1950s).  I'm helping a friend set up a new O-gague set and everything is working fine except the light on the bridge. 

He has a 6-37900 O-gague Lionel silver truss bridge that comes with a red light box that attaches to the bridge and contains two wires.  The light was separate and there are no instructions on how to attach it to the tracks (fast tracks).

Does anyone know how to attach this?   

Thank you,
Scott