protected void Page_Load(object sender, EventArgs e)
{
    System.Threading.Thread.CurrentThread.CurrentCulture = new CultureInfo("pl-PL");

    List<string> myList = new List<string>();
    myList.Add("Waszyngton");
    myList.Add("Helsinki");
    myList.Add("Moskwa");
    myList.Add("Warszawa");
    myList.Add("Vancouver");
    myList.Add("Wadowice");

    myList.Sort();

    foreach (string item in myList)
    {
        Response.Write(item.ToString() + "<br>");
    }
}