Click on the Categories you want to Include and then click on the Categories you want to Exclude from your search. Then further down the page, click on the Keywords you would like to Include and then click on the Keywords you would like to Exclude from your search. You can combine you selections by selecting Include these categories, exclude these categories and exclude these keywords without clicking on include any keywords.
The difference between a Category search vs a Key Word search is simple. Category relates to the whole transformation theme of the story. Where as Key Words relate to scenes or small parts of a story.
To save screen space, the descriptions of the Categories and Keywords have been removed. See Category Search or Key Word search if you need to read the descriptions.