Does your Camry have the 2.2 4 cylinder or the 3.0 V-6 engine? Both were used in that model year.
The bank 1/ sensor 1 oxygen sensor (Toyota calls oxygen sensors a/f sensors) is the one closest to the engine.
If you open the hood and look straight down at the space between the engine and the radiator, you will see the oxygen sensor you are looking for protruding forward from the exhaust manifold. The electrical connector for it is located up by the end of the valve cover on the drivers side of the engine.