StartupShortcut.cs

private string getShortcutPath()
{
    string startupPath = Environment.GetFolderPath(Environment.SpecialFolder.Startup);
    return System.IO.Path.Combine(startupPath, "myApp.lnk");
}

private void createStartupShortcut()
{
    WshShell shell = new WshShell();
    IWshShortcut shortcut = (IWshShortcut)shell.CreateShortcut(getShortcutPath());
    shortcut.Description = "Startup shortcut for myApp";
    shortcut.TargetPath = System.Reflection.Assembly.GetExecutingAssembly().Location;
    shortcut.Save();
}

private void removeStartupShortcut()
{
    string shortcutPath = getShortcutPath();
    if (System.IO.File.Exists(shortcutPath)) {
        System.IO.File.Delete(shortcutPath);
    }
}