These steps are the same whether you're adding your first email account or additional email accounts to Outlook. 

1. Select File > Add Account.

2. What you see next depends on your version of Outlook. 

For Outlook for Office 365 and Outlook 2016 

Enter your email address and click Connect

For Outlook 2013 and Outlook 2010 

Enter your name, email address, and password, and click Next

If prompted, enter your password again, then select OKFinish to start using your email account in Outlook.