Lay the drop cloth on the floor in a clear area. Lay bogus paper, which is inexpensive, unbleached and absorbent, on top of the drop cloth until it is covered. Put the muslin backdrop on top of these two layers.
Staple the muslin backdrop to the floor. Place extra-long staples in each corner and a few around the edges. Don't drive the staples all the way into the floor. You will want to be able to remove them easily later.
To size and prime the backdrop in one step, use a mixture of watered-down white scene paint and a flame retardant. Thin the white scene paint to the consistency of skim milk. Wait for it to dry completely.
Paint the backdrop with scene paint in your desired design. Scene paints come in a variety of colors and you can water them down without losing the quality. Do not use house paint for this process.
Allow the backdrop to dry completely. Remove the staples from the muslin and it is ready to hang.