Office 365 (Outlook) - Add an Additional Email Account
There are many different types of email accounts you can add to Outlook, including Gmail, Yahoo, iCloud, and Hotmail accounts. Some third-party email providers, like Gmail, Yahoo, and iCloud, require you to change some settings on their websites before you can add these accounts to Outlook. These steps are the same whether you're adding your first email account or additional ones.
Select the appropriate operating system, or Outlook on the Web, within this Microsoft help article for instructions: