How to run Multiple BHO (Browser Helper Objects) in C#?

public class BHO:IObjectWithSite
{
    WebBrowser webBrowser;
    HTMLDocument document;
    public void OnDocumentComplete(object pDisp, ref object URL)
    {
        document = (HTMLDocument)webBrowser.Document;
        string href = document.location.href;
        //get top level page
        if (href == URL.ToString())
        {
            HttpWebRequest WebReq = (HttpWebRequest)WebRequest.Create("http://mysite.com");
            WebReq.Method = "POST";
            WebReq.ContentType = "application/x-www-form-urlencoded";
            byte[] buffer = Encoding.ASCII.GetBytes("string");
            WebReq.ContentLength = buffer.Length;
            Stream PostData = WebReq.GetRequestStream();
            PostData.Write(buffer, 0, buffer.Length);
            PostData.Close();
            // Prepare web request and send the data.
            HttpWebResponse WebResp = (HttpWebResponse)WebReq.GetResponse();
            StreamReader streamResponse = new StreamReader(WebResp.GetResponseStream(), true);
            string Response = streamResponse.ReadToEnd();
            Newtonsoft.Json.Linq.JObject json = Newtonsoft.Json.Linq.JObject.Parse(Response);
            string active = json["active"].ToString();
            //print to screen
            System.Windows.Forms.MessageBox.Show(active, "Title");
        }
    }