Now, as you look at the egg again, notice how the top left side is much darker than the top right side. You can almost see where the egg is divided from light to dark, with medium darks and lights in between. Think of those areas as "chunks" of light and dark. In the drawing above, I "mapped out" where those chunks are. Draw them softly enough to not be noticed later on.

Fill in those areas carefully, making sure you aren't just "coloring it in."
Our light source is coming from the upper right. When the light hits the egg, it is bathed in brightness. That spot is called the "highlight." You won't need to shade anything there. Though the egg is in the light, it is blocking a portion of light from reaching the table it sits on. The "darkness" on the left side of the egg is shaded. The absence of light on the table is the egg's shadow.

It is best to put down the darkest value first to help you keep in perspective the mid-tones. (That would be the "grays" in between black and white.) Also, take notice of the bottom of the egg. Is the bottom left side as dark as the top left? No, actually it is much brighter because the table is reflecting the light right back up at the egg! So watch out for those easily-darkened "chunks." You may have a reflection that could really make your drawing pop off the page!

You may be wondering, "Shouldn't the whole back of the egg be the darkest part?" Well, aside from the reflections, shadows can overlap, making some portions a little darker than others. Also, with the shadows right next to the light on the table there will be more contrast, making the darks appear even darker.

Remember when shading that you don't want your lines to be streaky.  An egg is round, so any lines that you would want to been seen should have the illusion of wrapping around the egg. This can be easily accomplished with curved strokes. Soften the shadows and clean up any unruly lines or smudges that would distract from your finished work and--

--Viola!
You've shaded an egg!