How to open new window which has no menubar or other toolbars?

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (Session["Username"] != null)
        {
            if (Request.QueryString["SMS"] == "yes")
            {
                Label1.Text = "Message Submitted Successfully";
                //here I want to open new window
            }
            else
            {
                Label1.Text = "";
            }
        }
        else
        {
            Response.Redirect("Login.aspx");
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        Response.Redirect("GenSMS.aspx");
    }
    protected void Button3_Click(object sender, EventArgs e)
    {
        Response.Redirect("SchSMS.aspx");
    }
    protected void Button4_Click(object sender, EventArgs e)
    {
        Response.Redirect("AtnSMSD.aspx");
    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        Response.Redirect("ResSMS.aspx");
    }
}