Most help files have an Index. An Index is a list of keywords which link to Topics. Each Topic can have multiple keywords. Most users will search the Index first, so it is a good investment in time to think about what keywords you want to add to your Index. There are several ways to add Keywords to the Index, the simplest is to highlight some text in your topic, then right-click it and select "Add as a Keyword". You can also click on the "Index" tab and use the Index toolbar to add and delete keywords, but that is working on a Project wide basis.
Keywords by Topic
To look at a list of all the keywords that an individual Topic uses, click on the "Properties" tab, below the editor, and then click on the "Keywords" tab.
On the left you see a list of the keywords specific to the current Topic. To add a new Keyword simply click the [Add] button and type in your new keyword. To delete a keyword, select it and click the [Delete] button. It's as simple as that.