Here we assume that you do NOT yet have Outlook set up on your computer.
You only installed Office 365 and now start Outlook for the first time:
Outlook will welcome you and ask you to Enter your email address:
Please enter your email address in that field. For example firstname.lastname@example.org.
On the next screen enter your email password:
Outlook will detect all the necessary settings from our system.
You can now send and receive e-mail.