Multiple levels of authorization

[wagao...@gmail.com]

A multi level authorization system and a friend told me cancancan could help me out.
I took a read of documentation but couldn't figure it out. So I'll explain here.
Mi goal is to create a sys were:

User "John" from South department creates Jane
User Jane creates June an Paul
Users June and Pual creats Bob, Nat and Emilly

Also
User Peter from North department creates Rita
User Rita creats Beca and Lisa
Users Beca and Lisa creates Clara, Lory and Alexa

Now, each user can see only records made by theyr selves, or from users that are bellow than, but not above or from other departments.

How should I start with the models and everithing?