Your Microsoft account is an account you created that store all your Microsoft stuff. Things associated with MS like wallpapers and web browser favorites. You can use any email address to login to your Windows account. Since you used your Google email address you have a password you created when you created that google account. That username and PW are used when you access Google things like, Chrome favorites or Youtube. If you use that email to login into your Windows account it uses whatever password you created when you created that Windows account. Your computer information is also stored on the MS server in your account. You can use your MS Account to login to live.com (outlook .live.com) but you don't have to.
Navigate to your profile on the Microsoft website in your web browser. If prompted, enter your email and password and click Sign in.
Click Manage how you sign in to your account. This is located to the right of your profile picture.
Click Add Email. The button is located under the "Account" section.
Microsoft refers to alternate emails or phone numbers as ‘aliases’. If you see that term, that is what it is referring to.
Select “New” or “Existing” Microsoft alias.
Enter the email address. Creating a new email will prompt you to enter the email name and select an email service from a menu. Using an existing email will prompt you to enter the full address into a text field.
Click Add Alias. You will be taken back to the profile page and the new alias will be listed among your other emails.
Click Make Primary. This will appear next to each alias listed on the account (except the current primary alias). The address you select will now be the one that appears in your avatar when you log into your account.