Christmas scene backdrops can be made of a variety of materials, but two of the most common are muslin and canvas, materials that are inexpensive and take paint well. Use a fabric that hasn't been treated with flame retardant, because the coating left behind by the retardant will prevent the fabric from taking the paint evenly.
Unroll a plastic drop cloth over a wooden floor, such as a stage floor. Unroll the backdrop material over the drop cloth.
Staple the fabric to the floor using 2 to 3 inch-long staples. Staple around the edges of the backdrop, pulling the fabric taunt with each staple. Leave about one inch of staple exposed; this way they will be easier to remove after you finish painting.
Paint the entire backdrop with white scenic paint. A base coat of paint will shrink the fabric prior to painting images and will prevent your Christmas scene from becoming distorted. Allow the base coat to dry before continuing.
Snap a baseline with a chalk-covered string. Stretch the string across the backdrop where you want a baseline, or horizon line, for your Christmas scene. Secure one end of the string to the floor with a nail. Pull the string taunt across the backdrop and snap it against the backdrop, leaving a chalk line.
Paint your Christmas scene using the chalk line as a reference. Paint large structures, such as buildings or houses, first; these will act as guidance for smaller images in your Christmas scene. Use various painting techniques. For example, use small brushes to paint details or sponges to cover the ground with snow. Cut a sponge into a round shape and dip the sponge in white paint. Press the sponge into the backdrop where you want snow, such as on rooftops and the ground.
Place fans around the backdrop. Set the fans on low and leave them running overnight to help the backdrop dry faster. Remove the staples using a hammer and hang your Christmas backdrop.
Use a sample piece of the fabric to experiment with various painting techniques before beginning your backdrop.
Use professional scenic paints for the best results; these will give you more options for mixing and thinning.