Your question is rather vague, the first thing I would do is smell the wetness. It sounds kind of silly I know, but if it smells sweet your car is leaking antifreeze into the cabin and the most likely cause of that is a bad heater core. If it has no smell, It's just normal water from outside. if that is the case, check all of your door seals and make sure if they aren't damaged, letting outside water into your car.