I know this does not directly answer your question. But I would start learning WPF by reading a book. The learning curve for WPF is notoriously steep and there's always three or more ways to do something in WPF. I recommend reading a book so that you get a good sense of the WPF fundamentals. After that, I would use the online resources to fill in the gaps and to dig deeper.
WPF Books Recommendations
Anonline resource that I found useful when I first started out doing WPF when I started to work on Family.Show, was Beatriz Costa's blog. Definitely check out her earlier posts from 2006 and 2007.