private void button1_Click(object sender, EventArgs e)
{
form1 form1 = new form1();
form1.show();
}
private void button2_Click(object sender, EventArgs e)
{
form1.Hide();
form2 form2 = new form2();
form2.show();
}
private void button3_Click(object sender, EventArgs e)
{
form2.Hide();
form3 form3 = new form3();
form3.show();
}

.. Atleast I helped I guess