In your mail client you may use mail.web.net as the SMTP server address. You will need to specify port 587 or 1025 as most ISPs often block the default outgoing port (port 25).
Authentication is required; use your web.net username (not your full email address) and password. For example: If your email address is firstname.lastname@example.org - you would use "support" as your username. SSL/TLS is available as well to ensure a secure connection.