Roll out shade and place on a flat surface. Center the stencil on the shade, securing with adhesive spray and/or painters tape.
With the stencil as a guide, make dots of puff paint about every 1⁄8 inch. (It will feel like decorating a cake.) Don't fill in the stencil completely. Vary color in different parts of the pattern for a multi-colored look, or keep it simple and use one color of puff paint.
Let paint dry completely, according to manufacturer directions, to avoid smearing. Carefully remove the stencil from the shade to reveal pattern.
Repeat the process to fill shade as desired. Create a row of the design at the bottom of the shade for a simple finish. Fill the entire shade with the pattern for a colorful and fun look. A single stencilled design in the bottom center is a subtle way to bring the color scheme of the room to the window.