Print out a copy of the image that you want to use for the stencil. Tape the image to the contact paper using masking tape. Or, draw your image directly onto the contact paper with a pencil.
Place the contact paper on a cutting board. Cut the shapes of the stencil out using a craft knife. Make sure that you cut out the sections that you want painted, and that you leave in any necessary bridges to hold shapes in place.
Remove the original design section if you attached it with masking tape.
Peel the protective backing from the contact paper and attach it to the wall in the position where you would like to apply the stencil.