Lee's right. However, some places refer to a door that's not prehung as a "blank," which means that the lauan door is not drilled or mortised for hardware. The 3068 means that the door is three feet, zero inches (36") wide by six feet, eight inches tall (80"). You want a lauan door, because it will be completely flat (as opposed to a raised panel door), allowing you to maximize the glue surface to adhere your scenery base (many of us use foam) to the door.
Hope this helps,
Dave Foxx