close Popup and open new webpage

[faranak]

hi
I am having a problem closing a popup and open a new page when a button click in popup window. when i close popup,new web page open in popup window.What I want to do is close the popup and return to the original window.
Please help me.
thanks

protected void btnMoshtarakin_Click(object sender, EventArgs e)
    {
        if (txtElatMorajea.Text == "")
        {
            Literal1.Text = string.Format("<script type='text/javascript' >window.alert('{0}');</script>", "");
        }
        else
        {
            Session["Elat"] = txtElatMorajea.Text;      
            Response.Redirect("Parvande.aspx");
        }
    }