Painting and studying

I am listening to a DVD that is in a series.  It is by Quang Ho.  I have 4 DVD's about subjects, Painting the Still Life, Getting Started Basic's and two others.  He is an exceptional teacher, very deep in his observations and eagerness to make learning about painting simpler and faster for me.  Which is great considering my age and starting point.  I recommend them. www.quangho.com.

So, after listening a little to the Basic DVD I am stuck on Tone.  He said without Tone, your color will be wrong etc.  I will have to watch that part many times to understand what he is trying to get across to me.  I understand light and shadow, and some artists didn't use light and shadow, but did use Tone.  I thought it was light and dark, or the three degrees of it usually used in a subject.. like an apple.  So I am a little confused by it.  His DVD of Painting The Still Life will deal with using light and shadow.  So maybe it will help me understand tone.  So, if you draw a chair, you can draw it two ways.  The Chair itself, or what is around the chair to make the shape of the chair.  So, where does Tone fit in?  I am almost finished with my abstract painting and have named it "Summer Reflections".  I have details to do.  I finished my sail boat and learned a lot about painting water.  Yahoo.!!!