How do I send it if I want to use outlook express instead of microsoft outlook. Any Idea ?

Outlook express is not an automation server, so you can't automate it like you can Outlook. As Sergey says, you can send e-mail using MAPI. Another alternative is to use CdoSys for Windows 2000 and later if you have access to an SMTP Server either locally or on the network. If you use CDO, it does not matter what your e-mail client is because sending the e-mail like this does not depend on the e-mail client.