Creating new email address in Outlook

[MC147]

I am trying to set up a new email address for outlook.
I have Office 365.
When I login to Outlook on the Web, it seems I have an email address which is
outlook_<long random string>@outlook.com


I want one like <my name>@outlook.com
On the main page, there is an option to add a gmail account, but not to add another outlook account.
Should I be doing this somewhere else?
Can't find any helpful instructions that actually work.