How to login to Plesk Panel? https://www.youtube.com/watch?v=NedkklQJHmQ&t=5s
To create an email address on Plesk Panel: Go to "Mail". Click Create Mail. Type the email address before the @, and if you have many domains registered under your name, select only the domain name under which you want to create the email address.
Also, Specify your external email address, which will be used to reset the password in case you lose access to your primary email. Leave the Mailbox box selected.
Specify the mailbox size if you want to or you can use the default defined by the provider which is mostly unlimited if your service plan states so.
Specify your password consisting of five or more characters or you can also use a password generator.
Click OK and you are good to go.