I saw pb folder in the example resource always, and I don’t understand what use of those files in the folder. Please tell me, tks again.

Those are Pixel Bender files (source and compiled files respectively.) They are used for various things in the engine, especially when it relates to texture pre-processing or number crunching.

If you do not know about Pixel Bender, have a look here:
http://www.adobe.com/devnet/pixelbender.html

You don’t need to know how to use Pixel Bender, or even what it is, to work with Away3D though. It just uses Pixel Bender internally for some intensive tasks.

oh. I will read it late. Very thankful.