Day for night, quite literally, is taking the day and making it look like night. In this way the day is posing as night for your situation. To pull off day for night you use a combination of two filmmaking elements: specific exposure and filters.
You usually start by underexposing the image, and then you add different filters to change both the quality and sharpness of an image. In this way you try to mimic light that appears at least in direction as if it could come from night sources. Then through underexposure and filters you change the color and intensity of that light, making it look easily as if it could have come from a night time source in the dark environment of late hours.
The easiest way to do this is if you have a very bright natural light as this works well to mimic moonlight. Try to shoot outside when there are sharp shadows and fast fallow because this will help even more with the moon effect. Try to utilize the graduated filter in these situations and you can usually get away with underexposure at around three stops.