You're just steps away from using Yahoo Mail, Yahoo Finance, Flickr, and more when you sign up for a Yahoo account. Create a new account or use an existing email address from any email provider; you'll just need to provide a password, date of birth, and a mobile number.
An extra email address is a new address added to your current account, so you don't need to create a new Yahoo account just to get a new address. Unlike disposable addresses, your account supports only one extra email address.
Tips on picking a good email address: Your email address is used all the time, and for convenience's sake, you will likely keep that email address for years to come: this is why you should give some careful consideration when choosing a user name for your new Yahoo email address.