public Form1()
    {

        InitializeComponent();

  webBrowser1.Navigate("https://mese.webuntis.com/WebUntis/?school=HSS%20Freudenstadt#/basic/main");
        while (webBrowser1.ReadyState != WebBrowserReadyState.Complete)
        {
            Application.DoEvents();
        }

        GetElementBy("button", "Login", "title").InvokeMember("Click");
        while (webBrowser1.ReadyState != WebBrowserReadyState.Complete)
        {
            Application.DoEvents();
        }

    var Username = GetInputElement("Benutzer");

     string UN = "xxxxx";

          Username.SetAttribute("value",UN);



        var Password = GetInputElement("Passwort");
    string PWD = "yyyyy";
      Password.SetAttribute("value",PWD);

GetElementBy("button", "submit", "type").InvokeMember("Click");

    }}


public HtmlElement GetElementBy(string Type, string Name, string Attribute)
    {

        HtmlElementCollection theElementCollection = default(HtmlElementCollection);
        theElementCollection = webBrowser1.Document.GetElementsByTagName(Type);
        HtmlElement ReturnElement = null;
        foreach (HtmlElement curElement in theElementCollection)
        {
            if (curElement.GetAttribute(Attribute).ToString() == Name)
            {
                ReturnElement = curElement;
                break;
            }

        }
        if (ReturnElement != null)
        {
            return ReturnElement;
        }
        else
        {
            return null;
        }

    }

public HtmlElement GetInputElement(string Name)
    {
        HtmlElementCollection htmlcol = webBrowser1.Document.GetElementsByTagName("input");
        HtmlElement returnElement = null;
        for (int i = 0; i < htmlcol.Count; i++)
        {
            if (htmlcol[i].OuterHtml.Contains(Name))
            {
                returnElement = htmlcol[i];
            }

        }
        if (returnElement != null)
        {
            return returnElement;
        }
        else
        {
            return null;
        }

    }