the general gist of using ajax is:
you links trigger a jquery function on click, in the onclick function the category ID is passed.
the jquery function calls another page where there is a recordset that uses the passed category ID to look up the categories, and on that page, there is a repeat region to display the information for the selected category.
the jquery function uses innerHTML to populate a div on your page with the information returned from the other page.
This works the same with webassist code as it would with any other code.
If you need help setting this up, we can help you write the jquery code in a premiere support appointment: