Put blue, yellow, red and more white on the palette, spacing them well. You can also use burnt sienna but it is optional. Leave all the other colors in the box if you have a gift box.
Simply paint the different areas of color directly over your sketch. Since this study does not need to be detailed, you can try to do it with a paint knife. If any of the colors you choose do not please you, use the knife to scrape it and put this mixed paint on one edge of the palette in case you need a dirty brown. The mixture of the three primary colors will harmonize in the painting so the paint you remove can be separated and mixed with a little more than another color to make brown or light or dark gray. There is no waste with a simple primary pallet.
Continue experimenting with your color study until you have a simple and striking painting that you like, made with a broad brush and with few details. If necessary, do several studies to determine the mixes and colors you like. Make this little study with the paintings coming out directly from the tubes. You do not need oil or thinner for this technique. If you like the effect, you can make the big painting in the same way by simply using a paint knife and paint tubes that you apply to the canvas in big strokes, without oil or thinner.