Xml undefined.

Hi i  am Passing parameters to Plugin Using Secure or Unsecure Configuration Using Plugin Registration Tool 

but i could not get xml file.

i am following bellow links

http://blogs.msdn.com/b/crm/archive/2008/10/24/storing-configuration-data-for-microsoft-dynamics-crm-plug-ins.aspx?Redirected=true

http://srmscrm.wordpress.com/2013/10/22/pass-parameters-to-plugin-using-secure-or-unsecure-configuration-using-plugin-registration-tool-in-ms-crm-2011/

public class SamplePlugin : IPlugin
    {
     public SamplePlugin(string unsecureConfig, string secureConfig)
     {
     }
 }

Note ; 
geting unsecureConfig = null.

plz guide where i am going wrong.

Thanks