Sorry to reply again, but Moshu, that thread didn't give any explanation, and has been left unanswered.
Also, on the main page "menu" for the category area, how do I get it to only display the "top" categories, and if one clicks on that category, the subsequent page will then show links to the subcategories and their posts?
For example
Category:
A Cat
B Cat
C Cat
Are all top categories and that's all I want to see on the main index.php page.
But, A Cat has subcategories of Sub A1 , Sub A2 and Sub A3. So if I click on A Cat from the menu, the next page should display links to Sub A1, Sub A2 and Sub A3