Documentation is best conveyed by way of a brief tutorial for Indexer.
Create some test pages in your site, on one of them create a content block with this test text in it:
Aenean turpis nec hac, scelerisque nascetur hac turpis massa aenean porttitor cras. Etiam montes. Facilisis! Ut pellentesque natoque, urna? Augue? Vel! Placerat a cras elementum amet, rhoncus. Tempor proin turpis in, in, enim dolor hac dictumst?
Now go to the dashboard and click the Indexer settings link and you can create a keyword list.
In the text box to the right of SELECT LIST OR, type 'Latin' and click the 'Add new keyword list' button. You could use the Default list but this shows how easy it is to add a new list to your indexer settings.
Once you have received confirmation of your new list being created you should now see 'Latin' selected in the dropdown and below it you should now see some new items on the page.
In the text box to the left of the 'Add new keyword to this list' button enter 'cras' but don't click the button. Indexer matches are case-insensitive so you don't need to worry about adding to versions of a keyword such as 'This' and 'this'. Before clicking the button to add the keyword you also need to specify which page you want it to link to. Do this by clicking 'Select page' . Once you've selected a page you can click the button to add the keyword which should display a confirmation and appear below the page selection link.
Repeat this add process for a few other keywords, e.g. 'hac' and 'turpis'.
When you're done, navigate nack to the page you added the text text to and make sure you're not in Edit mode. You should now see the words 'cras', 'hac', and 'turpis' automatically converted into links to the pages you specified.
Additional features in the dashboard page are:
You can define as many lists and keywords as you wish and have the same keywords in different lists linking to different pages though all keywords in any one list must be unique.