Previously, I posted about the you could create an alternate name for Yahoo e-mail address, (click here for the post) and I received 1 of interesting comments;
1. Go to your right upper corner and click Settings
2. And go to Accounts and Import tab
3. On the second option, you could see this (as shown in the picture below). Click Send mail from another address
4. A new pop up window will show up. Then just proceed with your e-mail address. I didn't proceed from here, coz I can't come out with some name for this alternate e-mail.
Ok. Have a nice try !!