can someone explain how a "class" is setup?

Hi,
I have installed everything I could think of in my site, so far so good.
Now, I need to understand the teacher-student aspect of the edublogs site.
what exactly does a teacher do in the system to have a class setup?
what do individuals of the class do in order to participate?
is there a way to assign homework?
I am very puzzled by this, I am trying to understand it

Thank you