If overheating has caused your headgasket to leak first you need to find the problem. The most overlooked cause is the rad being plugged up with dirt. Spray the front of the rad with some sort of cleaner I recommend a citrus degreaser when the engine is cold. Use garden hose and spray from behind to clean it out if you have A/C you will need to unbolt the top bolts of the rad and push it back so you can flush out your condenser as well. Then of course you need to replace your head gasket because a leaking head gasket will destroy your engine.