Categories - How to add them to a page

Categories are made by adding

    [[Category:Timeline pages]]

at the bottom of a page (for the category 'Timeline pages').
It doesn't matter where you put the category code in a page, but for cleanliness of your editing page, please put it at the bottom.
To add other categories, simply add a new line, for example

    [[Category:Event pages]]

If you want to the category 'SMMA-HR' to be a subcategory of the category 'Biography pages' then simply add

    [[Category:Biography pages]]

to the page that was generated for the Category:SMMA-HR.

The software automatically generates pages with alphabetical lists of all subcategories and pages in a category.
See Special pages>Lists of pages>Categories.