C#

//Form1:
private string valueFromSecondForm; 

public string ValueFromSecondForm
get { return value; }
set { valueFromSecondForm = value; }  

private void button1_Click(object sender, EventArgs e)
{
     Form2 frm = new Form2(this);
     frm.Show();
}


//Form2:
public partial class Form2 : Form
{
    Form opener;

    public Form2(Form parentForm)
    {
        InitializeComponent();
        opener = parentForm;
    }

    private void button1_Click(object sender, EventArgs e)
    {
        opener.ValueFromSecondForm = valueFromForm2Textbox.Text;
    }
}

public static Program
{

   private static object _myTransferData = new object();

   //...

   static int Main(arg, args)
   {
      MyForm1.DataChanged += new FormDataChanged;
   }

   private static void FormDataChanged(object sender, EventArgs e)
   {
      // when you instantiate form2 later on, you can use
      //_myTransferData to pass your values
      _myTransferData = MyForm1.DataStorage;
   } 

}

Promance wrote:

want to transfer data between two form automatic two way, and response by click a button too.