Office 365 (Outlook on the Web) - How to Create a New Contact
Select the People icon from the lower left navigation bar if you are in Mail, Calendar, or Tasks - OR - if you are in another application, go to the top of the page, select the App launcher 
, and then select People.
1. To create a contact, select 
New and select Contact.
2. This will open a blank contact form. Fill in any details that you want. Select the
icon to see more options for that type of information. For example, if the person you’re adding to your contacts has multiple phone numbers, select the
next to
Phone to add phone numbers.
3. When you’re done, select
Save to save your changes or
Discard to cancel.