Not sure of the floor plan of your trailer, but somewhere there will be a wall plate with two cable jacks with a short loop of TV cable connecting them. They will be labeled "sat in" and "sat out", I think. The "sat in" side is the other end of the outdoor cable connection on the trailer, usually near the utility hook-ups.
Hook the cable tv supply to the outdoor connection and the cable box to the sat in connection.
Jeff & Cindy
'09 27FB Flying Cloud
'91 350 LE MH