96'ES-300:Malfunction Indicator Lamp

[rockit_mon]

The Malfunction Indicator Lamp started to stay on yesterday. But not the traction control. Fuel tank is full and it would appear from reading all the post it is an O2 sensor. I will have the local PepBoys check the codes for me. The problem is how do I now which of the four O2 sensors to replace, how are they replaced, and how do I just reset the darn thing. It would seem possible the MIL may just be a bit lazy. The car runs and looks perfect. Never a problem in the past. Your thoughts and suggestions would be most appreciated.

[lexusgui]

When you pull up the code it should tell you which sensor it is.
bank 1 sensor 1 is on back side of engine just after exhaust manifold