The trans cooler is internal to your radiator. If you stand at the front of your car looking under the hood, put your left hand down over the inside of the radiator end tank and you will see where two small metal lines come straight into the radiator end tank at a screw on fittings. The top one is output of the trans cooler. You disconnect that, put the hose on there and route it down to a drain pan with capacities marked on it. The trans will only pump fluid while the engine is running, so run it long enough to get a measured amount out (say 2 quarts) then stop the engine and fill that much new fluid back in. Keep doing this until you have replaced the entire capacity of the transmission cooling system. Helps to have a second person to keep starting and stoping the car.