From the Manufacturer
Note: The keys are inside the security file. You need to put the file on a floor or at knee level on a hard surface. With the palm on the lines/ridges on the black handle, we need to put constant pressure down on the lid and with the fingers, pinch the red long “button” up. This will open the file. Sometimes the water gasket seals create it a little harder to open but with use, this relieves it.