I'm going to assume that when you say "overheating" you are experiencing coolant and/or steam leaking out from under the hood.
If that's the case, then the first thing to check is where the leak is coming from.
BE VERY CAREFUL WITH THIS AS THE LEAKING FLUID OR STEAM IS VERY HOT!! For ALL the steps below, WAIT UNTIL THE ENGINE HAS COOLED!
If it's ...