Simulate login action to VBulletin using C#

I trying to write a program (C#) that can login and create new thread into VBulletin forums. I tried 2 way:

1) Use HttpWebRequest : Login is done. However creating new thread is fail. This is posting code:

public static void CreateNewThread(string url,string fId, string title, string message, string tag)
    {
        url += "newthread.php?do=postthread";

        HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
        //string re开发者_C百科sult = "";

        string values = "subject=" + title
                        + "&message=" + message
                        + "&tag=" + tag
                        + "&do=postthread"
                        + "&f=" + fId
                        + "&s="
                        + ""
                        ;

        req.Method = "POST";
        req.ContentType = "application/x-www-form-urlencoded";
        req.ContentLength = values.Length;

        ServicePointManager.Expect100Continue = false; // prevents 417 error

        using (StreamWriter writer = new StreamWriter(req.GetRequestStream(), Encoding.UTF8))
        {
            writer.Write(values);
        }

        HttpWebResponse c = (HttpWebResponse)req.GetResponse();
    }

When a execute the code above, no any theard has been created !

2) Use WebBrowser control:

 webBrowser1.Document.GetElementById("navbar_username").InnerText = "admin";
 webBrowser1.Document.GetElementById("navbar_password").InnerText = "123";

But I cant not submit because the has no name/id, and Login button is same ! Please tell me how to submit a form without form name/id and button name/id ?

Thanks !

Best regard,

Try simulating post data instead of filling out the form:

string postData = "username=Kurresmack&password=pw&action=login&url=/";
webBrowser1.Navigate("www.sweclockers.com/forum/member.php", "", System.Text.Encoding.UTF8.GetBytes(postData), "Content-Type: application/x-www-form-urlencoded\r\n");