I am working on a WPF project using VS2010 and .NET 4.0. I have custom PNG graphics for the various pieces of a vertical scroll bar. My goal is to create my own custom skin for
As reference material the link you provided is adequate. A more scholastic approach by Sacha can be viewed here which makes use of the base style which your link references.
Styling varies greatly; from merely changing a color to changing the entire look and feel. Modifying existing templates is a good place to start as you begin to uncover the concepts and parts associated with template's within the WPF framework. Editing a style can be trivial however it can also become extremely complex. This is all contingent on the desired outcome.