How do I handle views loaded based on conditions correctly?

[eluser]Unknown[/eluser]
I am making a system to help manage bills for a friend (and practice at CI). It will require you to login, then once to login it will take you to the overview page showing an overview for each months bill for the current year.

I currently have the controllers layed out like this:

Code:

/auth/         - Brings up the login screen
/auth/do_login - submits the login If successful user goes to /bills/, else the login is displayed again with the validation errors underneath.

/bills/        - Brings up the overview

Now I am wondering how I am supposed to correctly transition between the user correctly logging in -> bill overview. Or, generally speaking, the transition from from the job of one controller to another (My /auth/ controller, from what I understand, is not supposed to have anything to do with displaying a bill overview).

I currently have a redirect setup to go back and forth but it seems there must be a better way.

Thanks,
Thomas