how to use Windows Presentation Foundation

hi everybody

I am going to work in a new project which will be in .net framework 3.0.In the .net framework there is anew called Windows Presentation Foundation(WPF).my project is to reshape a site.Can somebody send me documents about wpf like

what is wpf.
features of wpf
benefits of wpf
how to use wpf in making web applications.

I will be waiting for the reply.

thanking you

avinash