Please see my comment to the question.
If you have some other problem, ask the author. Load the page of the article, locate "Comments and Discussions" at the end and click "Add a Comment or Question" to ask your questions. Or click here:
http://www.codeproject.com/script/Forums/Edit.aspx?fid=442654&floc=/Articles/19767/Basic-Illumination-Model-in-C[
^]. The author will get a notification and a chance to reply.
However, I suggest you study the article and source code in advance, and make your request clear enough.
—SA