Hi,
In your case try like this.
In your form button click
WiFi_Fast_Setup_Form1 objfrm= new WiFi_Fast_Setup_Form1(textbox1.Text);
if (objfrm.ShowDialog() == DialogResult.OK)
{
textbox1.Text=objfrm.newModifiedtext;
}
In WifiFast_Setup_form1 place on Ok and cancel button
public String newModifiedtext= "";
public WiFi_Fast_Setup_Form1(String txtvalues)
{
InitializeComponent();
newModifiedtext= txtvalues;
}
private void btnOK_Click(object sender, EventArgs e)
{
newModifiedtext="Now adding new text for test";
}