1. Create a new document. Choose the Elliptical Marquee Tool and make a circle, then fill the selection with the color you want.

Make a sphere 1

2. Then, choose a darker shade and paint the area where light doesn’t reach. Be sure to keep your selection.

Make sphere 2

3. Now choose a lighter shade, and then the highlight.

Make sphere 3

4. Finally, use the Healing Brush Tool to blend the shades together and make the image look smooth.

Make sphere 4