How do i go about this?

[Perad]

I half achieved it on this page .. http://www.jasonstanley.co.uk/UNC/

You see how you can click on "comments" and it displays the news article and the comments. This was a script which i found and modified. It wasn't very well explained on how it works.

I effectively want the above but 3 layers worth instead of 2.

I want the initial screen to show the categories with the number of articles in each categories.

Category 1 (5 articles)
Category 2 (3 Articles)
Category 3 (12 articles)

I have actually made this much, i just can't work out how to do anymore with php

When the user clicks on a category it will display the following.
--------------------
Category 1
--------------------
--Article 1
--Article 2
--Article 3
--Article 4
--Article 5

Finally the user will click on an article name and it will display the article.

------------------
Article Title
------------------
Article Content.

How would i do it? I thought i could create 3 functions, each one calling the relevant data then i would some how piece to it together. Unfortunately i can't find anything about this is my php book.