access dom of htm; modified by javascript

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C#

WinForms

How do i access the elemenets of a form generated by javascript in dom?
I am loading the webpage in webbrowser control.
when i tried to access the elements using getElementsByTagsName("input"), i get 0 elements

<SCRIPT type=text/javascript>  
        (function(){            
        function runElemGen() {
       var ElemGenForm = [{"label":"Email:","name":"ElemGen_email_field","oldName":"","value":"","ElemGen":"text"},{"label":"","name":"ElemGensubscribe","oldName":"","value":"Submit","ElemGen":"submit"}];
       ElemGenBuildForm({makeDivs: true, arr:ElemGenForm, place:"ElemGen-email-form-"});                
        }
      if (window.addEventListener) {
        window.addEventListener("load", runElemGen, false);
      } else {
        window.attachEvent("onload", runElemGen);
      }
    })();
</SCRIPT>