hello i am trying to make a cookie clicker for a school project but i dont know how to save multiple data intov your program u can find the save / load data under here its c# WPF

    *private void btnSave_Click(object sender, RoutedEventArgs e)
    {
        var OpgeslagenData = "opslag.txt";
        using(StreamWriter sw = File.CreateText(OpgeslagenData))
        {
            sw.WriteLine(globaleDingen.koekjes);
            sw.WriteLine(globaleDingen.aantalUpgraded);
            sw.WriteLine(globaleDingen.klick);
            sw.WriteLine(globaleDingen.upgrade);
            sw.WriteLine(globaleDingen.goldBars);
        }
    }

    private void btnLoad_Click(object sender, RoutedEventArgs e)
    {
        int koekjes;
        int aantalUpgraded;
        int klick;
        int upgrade;
        int goldBars;
        var OpgeslagenData = "opslag.txt";
        using(StreamReader sr = File.OpenText(OpgeslagenData))
        {
            koekjes = Convert.ToInt32(sr.ReadLine().ElementAt(1));
            aantalUpgraded = Convert.ToInt32(sr.ReadLine().ElementAt(2));
            klick = Convert.ToInt32(sr.ReadLine().ElementAt(3));
            upgrade = Convert.ToInt32(sr.ReadLine().ElementAt(4));
            goldBars = Convert.ToInt32(sr.ReadLine().ElementAt(5));

        }
        globaleDingen.koekjes = koekjes;
        globaleDingen.aantalUpgraded = aantalUpgraded;
        globaleDingen.klick = klick;
        globaleDingen.upgrade = upgrade;
        globaleDingen.goldBars = goldBars;
    }
}

}*

i hope anyone could help me please