Place your stencil in the middle of the shade just above the bottom hem. Faintly mark all four edges with a pencil. Remove the stencil, lightly apply spray adhesive to the back, and place the stencil back on the shade at your marks. Pour a small amount of paint in a saucer. Dab a damp sponge in the paint, and then lightly and slowly dapple it over the stencil until covered.
Tip: Start with a little bit of paint. You can always add more.