//*[@id="js"]/body/table[3]/tbody/tr/td[2]/table

/html/body/table[3]/tbody/tr/td[2]/table

//body/table[3]/tr/td[2]/table

public string GetDescription(string html)
{
    HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();            
    doc.OptionFixNestedTags = true; //Опционально, если требуется
    doc.Load(new StringReader(html));
    HtmlNode node = doc.DocumentNode.SelectSingleNode("//body/table[3]/tr/td[2]/table");    
    return node.OuterHtml;
}

input data-val-regex-pattern="[a-zA-Z0-9-]{1,}" data-val-regex="The field UserName must match the regular expression '[a-zA-Z0-9-]{1,}'." data-val-required="The UserName field is required." data-val="true" id="UserName" name="UserName" size="50" type="text" value=""

webBrowser1.Document.GetElementById("UserName").SetAttribute("value", "csharpcoderr");

HtmlDocument rememberme = this.webBrowser1.Document;
rememberme.GetElementById("helpbox").SetAttribute("checked", "true");       

private void button1_Click(object sender, EventArgs e)
{
    if (webBrowser1.ReadyState == WebBrowserReadyState.Complete)
    {
        webBrowser1.Document.GetElementById("UserName").SetAttribute("value", "csharpcoderr");
        webBrowser1.Document.GetElementById("Email").InnerText = "info@csharpcoderr.com";
        webBrowser1.Document.GetElementById("Password").InnerText = "11111111";
        webBrowser1.Document.GetElementById("ConfirmedPassword").InnerText = "11111111";
        webBrowser1.Document.GetElementById("Phonecode").InnerText = "7922";
        webBrowser1.Document.GetElementById("Phone").InnerText = "7946455";

        HtmlDocument rememberme = this.webBrowser1.Document;
        rememberme.GetElementById("helpbox").SetAttribute("checked", "true");               
    }
}

Ping Pinger = new Ping(); 
PingReply Reply = Pinger.Send("127.0.0.1"); 

List IPs = new List(); 
IPs.Add("10.1.1.12"); 
IPs.Add("10.1.1.15"); 
IPs.Add("OAOkomp1"); 
IPs.Add("192.168.173.160"); 
IPs.Add("www.google.com"); 
IPs.Add("www.amazon.com"); 
Ping Pinger = new Ping(); 
foreach (string ip in IPs) 
{ 
    PingReply Reply = Pinger.Send(ip); 
    Console.WriteLine("Ping " + ip + ": " + Reply.Status.ToString()); 
}

IntPtr nextClipboardViewer;

public Form1()
{
    InitializeComponent();
    nextClipboardViewer = (IntPtr)SetClipboardViewer((int)
                this.Handle);
}
[DllImport("User32.dll")]
  protected static extern int
            SetClipboardViewer(int hWndNewViewer);
[DllImport("User32.dll", CharSet=CharSet.Auto)]
public static extern bool
         ChangeClipboardChain(IntPtr hWndRemove,
                              IntPtr hWndNewNext);
[DllImport("user32.dll", CharSet=CharSet.Auto)]
public static extern int SendMessage(IntPtr hwnd, 
                                     int wMsg,
                                     IntPtr wParam,
                                     IntPtr lParam);

protected override void WndProc(ref System.Windows.Forms.Message m)
{              
    const int WM_DRAWCLIPBOARD = 0x308;
    const int WM_CHANGECBCHAIN = 0x030D;

    switch (m.Msg)
    {
        case WM_DRAWCLIPBOARD:
            DisplayClipboardData();
            SendMessage(nextClipboardViewer, m.Msg, m.WParam,
                        m.LParam);
            break;

        case WM_CHANGECBCHAIN:
            if (m.WParam == nextClipboardViewer)
                nextClipboardViewer = m.LParam;
            else
                SendMessage(nextClipboardViewer, m.Msg, m.WParam,
                            m.LParam);
            break;

        default:
            base.WndProc(ref m);
            break;
    }
}

void DisplayClipboardData()
{
    try
    {
        IDataObject iData = new DataObject();
        iData = Clipboard.GetDataObject();

        if (iData.GetDataPresent(DataFormats.Rtf))
            richTextBox1.Rtf = (string)iData.GetData(DataFormats.Rtf);
        else if (iData.GetDataPresent(DataFormats.Text))
            richTextBox1.Text = (string)iData.GetData(DataFormats.Text);
        else
            richTextBox1.Text = "[Clipboard data is not RTF or ASCII Text]";
    }
    catch (Exception e)
    {
        MessageBox.Show(e.ToString());
    }
}

protected override void Dispose(bool disposing)
{    
    if (disposing)
    {
        if (components != null)
        {
            components.Dispose();
        }
    }
    base.Dispose(disposing);
}

protected override void Dispose(bool disposing)
{
    ChangeClipboardChain(this.Handle, nextClipboardViewer);
    if (disposing)
    {
        if (components != null)
        {
            components.Dispose();
        }
    }
    base.Dispose(disposing);
}