How to insert Javascript/Jquery to my BHO using C#

Question

Hy guys
Î'm, creating my first BHO ( Browser Help Object) and i need help with this . I know that this is one of the best coding forums soo if i can't find here i will not find out .
 
The thing is :

  
  public void OnDocumentComplete(object pDisp, ref object URL)         {             if (URL.ToString().Contains("www.google.com"))             {                 HTMLDocument document = (HTMLDocument)webBrowser.Document;                   IHTMLElement body = (IHTMLElement)((IHTMLElementCollection)                                        document.all.tags("body")).item(null, 0);                 IHTMLScriptElement scriptObject =                 (IHTMLScriptElement)document.createElement("script");                 scriptObject.text = "alert('The script will add to the page  ');";                 scriptObject.src = @"\Resource\extension.js";                 scriptObject.text ="container.appendChild(input);";                  ((HTMLHeadElement)body).appendChild((IHTMLDOMNode)scriptObject);             }         }  

I'm trying with my BHO to manipulate a certain page But isn't working ... Can someone help to figure out how can i putt this extension.js to the page ? the extension.js just have the code to putt one textbox and the respective .css
 
Thanks for all