Once you've located this widget, click on the down arrow indicated by the green arrow to see the widget settings. The title is the title which will be displayed at the top of the widget in the sidebar it is located in. By default none of your post categories will be hidden. To hide certain categories, simply check the boxes located next to them. The purpose of this widget is to display a post tree. (You can find more information about widgets in general at https://codex.wordpress.org/WordPress_Widgets)

 

     On a page on your site, where the SP Post Tree widget is active, you will see the post tree with the categories that you set to visible. The entire widget is shown here in the green box. It can be used to navigate to individual posts, just by clicking on the links. The "Help Documentation" is just the title that was set. It is completely open to customization from the dashboard.