help.yahoo.com/kb/create-extra-email-address-sln3290.html

Learn how to create, use, and delete extra Yahoo Mail addresses.

help.yahoo.com/kb/SLN2.html

No. Learn how to create an alias or extra email address on Yahoo.

uk.answers.yahoo.com/question/index?qid=20090416015900AA1AcH...

For security reasons yahoo do not allow you to change your email address you need to open a new account to get a different address, but you can create a extra yahoo email address within your present account to do so use this link.

help.yahoo.com/kb/SLN3240.html

Keep your personal information private by using an alias for your Yahoo ID. By creating an alias, which masks your ID, you can communicate online without having to worry about exposing too much personal information.