Logon failure: unknown user name or bad password"

I am creating code to open website in vb.net and passing the use name and password to that site. But I got error " Logon failure: unknown user name or bad password"

This is my code. What's wrong in that

Dim domain As String = "google.com"
        Dim username As String = "Username"
        Dim password As New System.Security.SecureString
 Dim plainPassword As String = "password"
        For Each c In plainPassword.ToCharArray
            password.AppendChar(c)
        Next c
          Process.Start("C:\Program Files\Internet Explorer\iexplore.exe", "https://accounts.google.com/ServiceLogin?service=mail&passive=true&rm=false&continue=https://mail.google.com/mail/?tab%3Dwm&scc=1&ltmpl=default&ltmplcache=2", username, password, domain)