Configuring My Outlook Express

Yahoo has the procedure as well, but here is the MS way:
(Type the Q number in the search box at support.microsoft.com)

How to Configure Outlook for Yahoo! POP3 Account

Q296524

How to Configure Outlook for Yahoo! POP3 Account (Q296524)

Microsoft Outlook

SUMMARY
Yahoo! offers Post Office Protocol version 3(POP3) e-mail services as well as Web-based e-mail services. This article describes how to configure an Internet e-mail account with Microsoft Outlook.

You must be a member of the Yahoo! Delivers program to use Outlook to access messages on the Yahoo! servers.
How to Configure a POP3 E-mail Client
The following are the basic server settings for Yahoo! Mail:
Incoming Mail (POP3) Server: pop.mail.yahoo.com
Outgoing Mail (SMTP) Server: smtp.mail.yahoo.com
Account Name/Login Name: Your Yahoo! Mail name (your address without the "@yahoo.com")
E-mail address: Your Yahoo! Mail address (i.e. user@yahoo.com)
Password: Your Yahoo! Mail password

How to Add a New E-mail Account to Your Existing Profile
On the Tools menu, click E-mail Accounts .

Click Add a new e-mail account , and then click Next .

Click the Add button.

Choose "POP3" and click next.

Enter your e-mail account information.

In the Your Name box, type your name as you would like it to appear.

In the E-mail Address box, type your Yahoo! e-mail address, for example, user@yahoo.com.

In the Incoming mail server (POP3) box, type pop.mail.yahoo.com .

In the Outgoing mail server (SMTP) box, type smtp.mail.yahoo.com .

In the User Name box, verify that everything before the at symbol (@) symbol of your Yahoo! e-mail address is displayed.

Enter your Yahoo! password.