You will need a sheet or cloth, grey or white big enough to cover your window and drape the floor, an orange light bulb/lamp and a fan.  Tack the cloth to the top of the window frame INSIDE the house.  Now take the bottom edges and pull the cloth back about ten inches from the wall…hold in place with shoes or canned food...this creates a space for the light that WON'T TOUCH THE FABRIC.  Put the lamp on the floor or small box so it is under the window in front of the cloth putting a spooky glow onto the fabric, then put the fan on low and point it so it blows on the cloth.  From outside this looks like there are flames dancing in the window!!! (You can only see this at night!)