How to add delete, update, edit button in gridview ?

Dear All, 
 May i know how to write in the delete, update or edit button in the griview  based on below code ?
 
<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="WebForm2.aspx.cs" Inherits="acmkweb.WM.WebForm2" %> <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"> </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <asp:TextBox ID="TextBox1" runat="server"/> <asp:TextBox ID="TextBox2" runat="server"/> <asp:DropDownList ID = "Drop1" runat="server" AutoPostBack="false" ></asp:DropDownList> <asp:Button ID="Button1" runat="server" ...