Post form data to other page

Hi, I have cloned the LogonMiniForm and I need to post the form's fields( UserName, Password Textboxes) value to some external url. I have put the external url in Default Redirect URL property of the user control. But when I click the button it is going to the external url but not able to see the posted form field's value, while checking in the Form Data under Network tab(chrome).The Form tag is in PortalTemplate.aspx,so I have put another Form tag in the user control without keeping runat=@server@ property. And I also tried without keeping this form tag in the user control but result was the same.Could you please help me on how to post form field value.Thanks.