2001 Ford Focus COOLANT LEAKAGE

Engine Cooling problem
2001 Ford Focus Front Wheel Drive Automatic 108000 miles

HI

There is coolant leaking from our car, but don't know from where. It doesn't leak everytime, mostly after a long drive when the car is at rest it leaks.
How do I find where is the leak from and how do I fix it?
There doesn't seem to be any problem of car overheating or smell or anything else. Thanks.