private void Button_Click(object sender, RoutedEventArgs e)
{
string s = null;
if (Qualitative.IsChecked == false)
{
s = "Qualitative";
}
else
{
s = "Quantitative";
}
add.AddGoal(NameForTask.Text, DescriptionOfTask.Text, First_Date.SelectedDate.Value, Second_Date.SelectedDate.Value, s);
MessageBox.Show(Second_Date.SelectedDate.ToString());
MainWindow mw = new MainWindow();
mw.Show();
this.Close();
}