Measure the length and the width of the cellar's ceiling and add between 1 and 2 feet to each measurement. The more fabric you use, the deeper the drape will be.
Cut a rectangle of fabric that matches the measurements you found in step 1. Depending on the size of the fabric, you may need to sew several rectangles together to get a rectangle that's large enough.
Locate the center of the fabric and mark it with a pen.
Climb a ladder placed under the center of the room, ensuring first that the ladder is sturdy and that you take safety precautions. Carry the fabric and a staple gun up the ladder with you, or have a friend hold the ladder and hand these items to you when you're at the top.
Staple the spot on the fabric that you marked with a pen to the center of the ceiling.
Staple the four corners of the square to the four corners of the room, allowing the fabric to billow from one staple to the other.
Staple the edges of the fabric to the edges of the ceiling.