Follow the lower radiator hose back the the engine and it will end at the thermostat.
Here are the replacement instructions
REPLACEMENT DRAIN COOLANT REMOVE BATTERY REMOVE AIR CLEANER ASSYDisconnect the MAF meter connector and wire clamp. Disconnect the VSV connector for canister closed valve (CCV) and air hose. Disconnect the 3 vacuum hoses. Loosen the hose clamp. Remove the air cleaner cap. Remove the air filter. Remove the 3 bolts and air cleaner case.SEPARATE RADIATOR HOSE OUTLET REMOVE WATER INLET PIPERemove the bolt and water inlet pipe.REMOVE WATER INLETRemove the 3 bolts and water inlet.REMOVE THERMOSTAT
INSTALL THERMOSTATInstall a new gasket to the thermostat. Align the thermostat jiggle valve with the upper stud bolt, and insert the thermostat in the water inlet housing. HINT: The jiggle valve may be set within 15° of either side of the prescribed position.INSTALL WATER INLET Torque: 8 Nm (82 kgf-cm, 71 inch lbs.) INSTALL WATER INLET PIPEInstall a new O-ring to the water inlet pipe. Apply soapy water to the O-ring. Connect the water inlet pipe to the water inlet. Install the bolt holding the water inlet pipe to the cylinder head. Torque: 20 Nm (204 kgf-cm, 15 ft. lbs.) INSTALL AIR CLEANER ASSY Torque: 5 Nm (51 kgf-cm, 44 inch lbs.) ADD COOLANT CHECK FOR ENGINE COOLANT LEAKS