The Help menu provides access to the online help, which basically contains the same content as this book.
The help is also context-sensitive, which can be accessed in several ways:

To see a tool tip for an icon, hold the cursor over the button for a second or two. The tool tip will appear, showing the name of the tool.

Tip: Look in the Help menu to see a list of keyboard shortcuts.Look in the Help menu for the Tip of the Day for helpful hints.