same way you replace any sensor.
driver side bank 1 before cat
usually bank 1 is the bank with # 1 cylinder in it and sensor # 1 is the front o2 sensor(usually in the manifold). You will need a O2 sensor socket or a 22mm wrench or deep socket.
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.
Replace bank one O2 sensor
O2 sensor circuit bank 1 sensor 2 no activity. Check the wiring and connections to bank 1 sensor 2 O2 sensor, if all looks good replace the sensor.
Bank 1 sensor 1 is upstream bank 1 sensor 2 is downstream
Replace it. Sensor 2 is the one AFTER the catalytic converter.
Bank 1 is the side of the engine that includes cylinder number 1, bank 2 would be the other side. Sensor one is before the cataylitc converter, sensor 2 would be after. BUT... IF one sensor has failed, you may as well replace the other at the same time. It will be going soon.
Bank 1 is the bank that sits closest to the front of the vehicle. Bank one is the bank with cylinder # 1. You have 4 oxygen sensors, (bank 1 sensor 1, bank 1 sensor 2, bank 2 sensor 1 and bank 2 sensor2). Follow the exhaust from the head of bank 1. The first sensor you come to is sensor 1, the second is sensor 2.
bank one would be the passenger side
Replace it.