I put antifreeze in my car bcuz it starrs to overheat. Maybe about 2 week later i have to put more in. When car is parked for hours i dont see any sign of antifreeze leaking. What can be the problem ?

Hello, it is very difficult to know without pressure testing your cooling system and evaluating the vehicle in person what the problem could be. You could have a leak that you may or may not be able to see; it could be internal to the engine, or external. The cooling fan may or may not be working as designed, depending on engine coolant temperature. It would be inappropriate to guess at the cause of concern without hands on evaluation.