Bank 2 refers to the side of the engine opposite the number one cylinder, on your vehicle that is the drivers side. Sensor 1 is the first sensor, the one before the catalytic convertor and sensor 2 is the one after it.
That is the O2 sensor behind the catalytic converter.
on the transmission housing appx 12o'clock
Driver's side, after the catalytic converter.
it is the upper stream o2 sensor before the convertor
That is the O2 sensor that is screwed into the front of the catalytic converter.
Bank 2 is the passenger's side of the engine and sensor 2 is behind the catalytic converter on that side.
where is the bank1 o2 sensor at and how do i change it please i need your help
its where the #1 cylinder is that's bank one
Assuming you mean P0135, that would be O2 sensor heater circuit malfunction (bank 1 sensor 1). If the wiring to bank 1 sensor 1 is not damaged, it is probably a bad bank 1 sensor 1 O2 sensor. Replace it.
The bank 1, sensor 3, O2 sensor would be the O2 sensor post cat.
The bank 2 pre cat O2 sensor is in the rear exhaust manifold, the bank2 post cat O2 sensor is under the car after the catalytic converter, P/S nest to transmission.
It actually screws into the middle of the cat.