It's on the side of the throttle body. On our V6 I unbolted it and pulled it back from the TB to hose out the guts. On the I4 I believe there is a square or triangular hole in TB into which you can spray cleaner. A search for IAC should turn up more specific information.
You can download a manual here which should provide some additional guidance... http://oregonstate.edu/~tongt/camry