Message Box in asp.net/ c#

Question

i want to show message in messagebox "Data Saved successfully" when click submit botton
i use below code but message box not show plz send me solution for this
protected void btnSaveUpdate_Click(object sender, EventArgs e)
{

objclscp_BlockFngoTargets.Insert();
MessageBox("Data Saved Successfully !");

}
private void MessageBox(string msg)
{
Label lbl = new Label();
lbl.Text = "<script language='javascript'>" + Environment.NewLine + "window.alert('" + msg + "')</script>";
Page.Controls.Add(lbl);
}
 
but above code not give any responce
i also use one more code but same problem
private void MessageBox(string message)
{
if (!string.IsNullOrEmpty(message))
{
Response.Write("<script type=\"text/javascript\" language=\"javascript\">");
Response.Write("alert('" + message + "');");
Response.Write("</script>");
}
}