Interacting with web page controls

[mbewers1]

Hi there, I have the following code

String strResult;
        WebResponse objResponse;
        WebRequest objRequest = HttpWebRequest.Create(strURL);
        objResponse = objRequest.GetResponse();

        using (StreamReader sr = new StreamReader(objResponse.GetResponseStream()))
        {
            strResult = sr.ReadToEnd();
            sr.Close();
        }
        return strResult;

which embeds an external web page (DOI Resolver) into my own site, the screenshot of which is attached.

What I can't understand is how is it possible to code a means to allow the user to interact with the controls of the website e.g. - pressing 'Go' should redirect them to the same page as if this site were being used on its own.

Matt