Flow of Code

Can u please explain the flow of any one module like Poll how it works in nopcommerce.
From creating the
==>usercontrol (PollAdd, PollDetail.....)  ,
==> Poll.aspx,..   ,
==> BussinessLogic   (Poll.cs, PollCollection.cs, PollManager....)  ,
==> DataAccess (DBPoll.cs, DBPollCollection.cs, DBPollProvider....)  ,
to
==> DataAccess.SqlServer  (SQLPollProvider.cs).