Roles and permissions

Hi
Apologies if this has already been answered - I have had a good look and not found it. One option may be Nick Latronica's post about different role / different entry in header.html (thanks everyone).

I Have been asked to have a site which has content that is visible depending on the user:

1. guests auto login and can see a few topics, post only to a questionnaire and see course calendar entries ( for example 1 and 2)
   
2. users type 1 can see and use access those plus a few more topics & resources (for example 1 - 4)
   
3. users type 2 access a different group of topics (for example 1,2, 5,6)
   
4. super users type 3 can pretty much act like course creators

We can easily take guests to a course by a link in a topic on the front page (as often used), and simply add links in header.php for that course's theme to restrict navigation.

The question is how do I hide the various sections/topics from the different users? Using roles must be the way but I do not seem to fathom it. The information all inter-relates and so putting it on one course is preferred. Only the super-users need some technical knowledge, the rest need it as plain to use as possible.

Many thanks

Ed