When in any of the Office 365 Apps (From Email to Calendar...) There is a Help pane in the form of a question-mark icon (see screenshot).

The Help pane lets users search for help about the application they are using. Simply click on the question mark symbol in the upper right corner and the "Help" pane opens up. (click on ? again to close it) Now all you have to do is type in your question and you will be presented with choices to pick that relate to the question you asked.

That's it! The "Help" in Office 365 is quite comprehensive and will be able to answer most any question you have about using Office 365.