combobox

Question

hi,
 i placed a combobox in a form inside a groupbox and i added items to it at design time itself using th property pane.i have even placed a button in the same form ,which would direct to another form and  there i have placed a textbox ,after getting input from the user i want it to be added to the items already existing in the combobox in the previous form.
i have used th following code
Form1:
private void button1_Click_1(object sender, EventArgs e)
{
Form2 fr2= new Form2();
fr2.Show();

}
 Form2
private void button1_Click(object sender, EventArgs e)
{
Form1 fr1 = new Form1();
fr1.comboBox4.Items.Add(textBox1.Text);
fr1.Refresh();
}