Where is the radiator cap located

Radiator has no cap. the plastic bottle on the side is where to put or add coolant to the system. if engine hot wait until cool down before you open cap as system may be pressurized and can burn you.

Thanks for the picture. I have a leak in one of the hose. So can i pour radiator stop leak in that reservoir tank to stop the leak or do i need to buy something else?

Stop leak not recommended. you can add it to the bottle, but my advice is to fix the leak as it will cost more on the long run if you add stop leak
and it may or may not work. why take the chance have it fixed correct the first time.
good luck!