How to wrice code in minimize button click event in c# .net windows application?

Try this EDIT May use Resize Event to do it,
private void Form1_Resize(object sender, EventArgs e)
{
if (this.WindowState == FormWindowState.Minimized)
this.Hide();
}

Then using the FormClosing Event to cancel Close and minimize the Form as below
private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
if (e.CloseReason == CloseReason.UserClosing)
{
e.Cancel = true;
this.WindowState = FormWindowState.Minimized;
}
}