How can I open the second form in C# without hanging up, so that the first one closes?

Question

C++ / C#

Prescribed

Form2 f = new Form2();
                    f.ShowDialog();

The second form opens, but it freezes. And the program just doesn't work.
Question: How can I open the second form without hanging up and at the same time close the first one?

Answer 1

f.Show();

Answer 2

Thank you for the correct wording of the question)
I myself had to think and look on the Internet and this is what I found. Let me tell you right now, I did it.
private void Button1_Click(object sender, EventArgs e)
{
MainForm Main = new MainForm();
this.Hide();
MainShowDialog();
this.Close();
}
as you can see, I also brought with the button Button. so that everything goes well.