Me, too. I hate this paradigm shift tuff.
Fro Wolsky's book:
Library is a container for events and projects that are used in one production. But that's a general principle, stuff in a library can be used in other projects and events.
The FCPX Library is like FCP7 project (vaguely resemble your folder structure and the organization of a drive)
The FCPX event is like FCP7 bin (but not really because you can't organize freely like in a bin. It's lame.)
The FCPX project is like FCP7 sequence or timeline (and you only get one! Just as lame.)
But I just got here first. Others will have better explanations for you.