Current limiting resistor needed in series with one lead. When connected directly to DCC voltage, Litchfield Station, LLC recommends a 750 to 1500 ohm resistor for white LEDs. The lower the resistor value, the brigher the light, but the shorter the life of the LED. With a 1000 ohm resistor, expect a life of about 5000 illuminated hours (over 6 months of 24 hours a day, everyday). Use 1.5K to 2K resistors for colored LEDs.
The longer lead is the anode and connects to the positive voltage (blue decoder wire).
The Orange Led can possibly also be used for rotary beacon lights.