magic.
lmao c; kidding.

you need yo use a camera that you can control it’s shutter speed.
(like an SLR or some types of digitals)
go outside at night or into your room with it completely dark or mostly dark.
set the shutter speed for however long you think you’re gonna take. (i usually use between 15 and 30 seconds)
use a tripod or table or anything to hold the camera COMPLETELY STILL.
press the shutter and run out in front of your camera, turn the flashlight on and start drawing c:(you wont be seen in the picture)

hope this helped(: