how to add checkbox to datagrid

Hi
    iam a fresher can any one helpme out how to add checkbox to a datagrid. using c#

<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="ShiftUpdate.aspx.cs" Inherits="Manual_Sanctions_ShiftUpdate" Title="Untitled Page" %>
<%@ Register Assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"  Namespace="System.Web.UI" TagPrefix="asp" %>
<%@ Register src="~/UserControl/Calender.ascx" tagname="Calender" tagprefix="uc1" %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %>
<%@ Register src="~/UserControl/TimeFormate.ascx" tagname="TimeFormate" tagprefix="uc3" %>

Shift Updation                   Date Range From Date To Date Selection Mode                                                        Applicable Applicable Employees                                runat="server" AutoGenerateColumns="False" Width="136%"  AllowSorting="True" AllowPaging="True" PageSize="20" onrowediting="dgApplicable_RowEditing"  onpageindexchanging="dgApplicable_PageIndexChanging" Height="127px"          style="margin-right: 75px"          onselectedindexchanged="dgApplicable_SelectedIndexChanged" >                                      AllowSorting="True" AllowPaging="True" PageSize="20" onrowediting="dgAppEmployees_RowEditing"       onpageindexchanging="dgAppEmployees_PageIndexChanging" Height="51px" >

AllowSorting="True" AllowPaging="True" PageSize="20"  Height="51px" >                                                                                              Change Type