Open or close the navigation pane
The navigation pane is located to the left of the topic pane. It contains Contents and Index tabs, which provide multiple entry points into the Help.
If the navigation pane is not already open, click 
at the left edge of the topic pane to open it.
Tip: The state (open, closed) of the navigation pane remains the same between Help viewing sessions. For example, if you close the Help window with the navigation pane closed, it is closed when you open Help again.