^^ same here. Here is how i replaced my upstream sensors, the first picture shows the upstream and downstream sensors and their location. The downstream sensors are much easier to get to and just unplug the wire, follow it and plug in the new one. one recommendation is to get the O2 sensor socket that is shortened, not the long one in my post because it will be hard to unscrew the old sensor and screw in the new sensor.
how-to-replace-oxygen-sensors-t573400.html