How to use blocks?

I cannot seem to figure this out.

 

Looking at the book but still does not make sense to me.

 

In my layout I want to define a sidebar area that will change depending on the page being viewed.

But I do not want to extent the view, I want to in the layout its self.

 

Has anyone figured this out or has any insight that might help me?

Examples of what you did or how you did it?

 

Thanks,

 

Dave