It's on the top of the exhaust pipe in front of the catalytic converter. It will have an aluminum shield snapped onto it and a shielded wire at the top. These unplug from the harness a few inches from the sensor. Find a wrench that fits and unscrew it. Lay both sensors out and cut the plug off the old and with a crimping tool install them on the new sensor. Put some anti seize compound on the threads and install the new sensor and plug it up. Here's where it gets sticky. You may have to erase the fault code if the check engine light came on. For that you'll need more than my help.