I working on an app with user authorization. It has a `List` and `User` classes. The authentication was built with Ryan Bates <http://railscasts.com/episodes/270-authentication-in-rails-3-1>

I'm not sure about authorization process. I read about `cancan` gem. But i could not understand.

I want to achieve this:

1. User only able to view/edit/delete his own list.
2. User only able to view/edit/delete his own profile(user class).

I don't implement user level right now. No guess or admin.

How to use before\_filter method in `list` and `User` controller with `current_user` instance?