Code P0141 and P0137

Wow...more problems with the car.
2000 Grand Prix GT 3.8 V6
Originally got P0137 code about 200 miles down the road from when I bought it...so went to autozone bought the new sensor and installed it where they said it belonged. Now I am wondering if i installed it into the correct location. I put it right where the exaust manifold bends down from the middle back of the engine bay and plugged it in. Another 200 miles down the road today and I get both P0137 coming up and also P0141. I am wondering whether or not I installed it in the correct spot or what is going on. How many oxygen sensors are located in this car and does anyone know where I can find a diagram explaining the different spots and names of where they are at?

B.T.W. This one is o2 sensor 2 in bank 1

:banghead:

Unfortunately you changed the wrong sensor. Change the sensor behind the cat. It is also possible that the cat is bad and causing the problem but changing the sensor will give you an idea especially if the code comes back. Once you have changed the sensor have the code cleared so that you don't confuse it with a stored code should the light come back on.