Multiple Checkbox list

aspx

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication1.WebForm1" %>
<asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="FeaturedContent" runat="server">
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="MainContent" runat="server">
    <asp:Panel ID="panelFilter" runat="server">
       
    </asp:Panel>
</asp:Content>

C#
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace WebApplication1
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            CheckBoxList objCheckbox1 = new CheckBoxList();
            objCheckbox1.ID = "objCheckbox1";
            objCheckbox1.AutoPostBack = true;
            objCheckbox1.SelectedIndexChanged += SelectedIndexChanged;
            CheckBoxList objCheckbox2 = new CheckBoxList();
            objCheckbox2.ID = "objCheckbox2";
            objCheckbox2.AutoPostBack = true;
            objCheckbox2.SelectedIndexChanged += SelectedIndexChanged;


            objCheckbox1.Items.Add(new ListItem("Items 1", "Items 1"));
            objCheckbox1.Items.Add(new ListItem("Items 2", "Items 2"));
            objCheckbox1.Items.Add(new ListItem("Items 3", "Items 3"));
            objCheckbox2.Items.Add(new ListItem("Items 4", "Items 4"));
            objCheckbox2.Items.Add(new ListItem("Items 5", "Items 5"));
            objCheckbox2.Items.Add(new ListItem("Items 6", "Items 6"));

            panelFilter.Controls.Add(objCheckbox1);
            panelFilter.Controls.Add(objCheckbox2);
        }

        protected void SelectedIndexChanged(object sender, EventArgs e)
        {
            CheckBoxList obj = sender as CheckBoxList;
          
            List<ListItem> selected = obj.Items.Cast<ListItem>()
                                        .Where(li => li.Selected)
                                        .ToList();
        }
    }
}