o2 sensor

I have a 2001 Stratus R/T 3.0L V-6. Engine light has came on. The code is (OXYGEN SENSOR BANK 1, SENSOR 2). I have (4) o2 sensors on this engine. The engine sits sideways in this car. What I need to know is where is this o2 sensor located? I know sensor 2 is one of the down stream sensors, but I don't know which side is bank 1. Is it the side of engine facing radiator or the side of engine facing firewall ???