To show a new Form on click of a button in C#

This worked for me using it in a toolstrip menu:

 private void calculatorToolStripMenuItem_Click(object sender, EventArgs e)
 {
     calculator form = new calculator();
     form.Show(); // or form.ShowDialog(this);
 }

1.Click Add on your project file new item and add windows form, the default name will be Form2.

2.Create button in form1 (your original first form) and click it. Under that button add the above code i.e:

var form2 = new Form2();
form2.Show();

3.It will work.