Hiding a windows form.

Please see my comment to Solution 1.

So, there is another technique which you could allow you to work with two different main form one by one. Let's say, you have two form classes; first one is your single-use form you wanted to hide after use forever, call if IntroductionForm, and another one is your "permanent" main form; call it MainForm.

using System.Windows.Forms;

//...

        static void Main() {
            Application.Run(new IntruductionForm()); // during the use of this form, eventually close it instead of hiding
            // you won't need the instance of IntruductionForm, anyway, so it will be disposed; you won't be able to show it again,
            // but the resources it uses will be reclaimed, which is good
            Application.Run(new MainForm()); // since this point, everything goes in a usual way
        }

//...

It is important to understand that a form instance becomes a main form when it is used as an argument of Application.Run; unlike other forms, when a main form is closed, the method Application.Run returns.

This explains how it works.

—SA

here is a sample example for you:
scenario: having two textboxes with a button opening a new form if values are correct

Form2 f2 = new Form2();


       private void button1_Click(object sender, EventArgs e) // event of first forms button
       {

           if (textBox1.Text== "test" && textBox2.Text=="test")
           {

               f2.Show(); // will display new form
               this.Hide(); // hiding of current form
           }
           else
               MessageBox.Show("Entry not valid");
       }