Open your Outlook express application.

Click the Tools menu and select Accounts..
That will bring up the following screen..

Click the Mail tab to bring it to the front. This displays a window containing your Internet email accounts. 
To modify your existing e-mail account, click its name and press the Properties button.

To rename an old account, type a name for it in the Mail Account field. (Changing your account name does not affect the operation of your email account)...

Enter the following in the User Information area:
Name: Enter your full name as you would like it to appear on your email messages.
Organization: This is optional. Type in the name of your business or group. This will be placed on all messages you send to newsgroups.
E-Mail Address: Enter your e-mail address for this account.
Reply Address: If you want your recipients' replies to go to another email address, type it here. If you don't enter anything here, check the box “Include this account…” replies will go to your email address.
Click the Servers tab...

My incoming mail server is : POP3.
Incoming Mail (POP3) as supplied.
Outgoing Mail (SMTP) of your ISP. You may need to call your ISP or visit their website to obtain this information.
If you are the only person who uses this computer to access the Internet, click Log on using to store your username and password in Outlook. Enter your username in Account name and your password in Password.
If others use this computer to access the Internet, leave the password field blank, so Outlook Express will prompt any user for a password before checking and sending e-mail.
Press OK to close the Properties window.
Click Close to close the Accounts window and save your changes.