Microsoft is offering short online training videos/tutorials on how to use Outlook. These tutorials apply to Outlook versions 2013 and newer. They provide assistance with standard program functions such as creating, sending and managing emails, as well as how to organise your inbox, contacts and calendar/s.
The Outlook for Windows training portal can be accessed here.
If you are using Microsoft Outlook 2013, training can be found here.
Microsoft also offers training for Outlook for Mac.