Ajax实现登陆界面无刷新登陆很急
要求用Ajax控件实现,请问需要添加哪个控件在什么部位,半桶水菜鸟求助啊.
  <form     id= "PostForm "   runat= "server "     >
<table   width= "100% "   border= "0 "   cellpadding= "2 "   cellspacing= "0 "   align= "center "   style= "height:   256px ">
      <tr>  
      <td   rowspan= "3 "   align= "center "   valign= "middle "   style= "width:   35% "> <br/> <br/> <img   src= "./skins/2004/images/border_login/mainpic.jpg "   alt   = " "/> </td>
      <td   colspan= "3 "   valign= "top "> <span   style= "padding-top:1px; "> <img   src= "./skins/2004/images/login_logo.jpg "   alt   = " "/> </span> </td>
      </tr>
      <tr>  
      <td   colspan= "3 "   valign= "top "   style= "height:   130px ">
<table   width= "80% "   border= "0 "   cellpadding= "0 "   cellspacing= "0 ">
<tr   valign= "top ">  
td   colspan= "2 "   height= "15 "> <font   style= "font-size:11pt "   color= "#7685A2 "> <strong> 用户登陆 <br   /> <br   />
                  </strong> </font>
                  </td>
                  </tr>
                  <tr>  
                        <td   width= "28% "   height= "25 "> 用户名： </td>
  <td   width= "72% ">   <input   type= "text "   name= "txtUserName "     class= "smallInput "   cTitle= "用户名 "   cType= "loginUser "   allowEmpty= "false "   size= "25 "     id= "txtUserName "   runat= "server "   maxlength= "20 "   tabindex= "1 "     onkeydown= "keyDown(); "/> </td>
                  </tr>
              <tr>  
        <td   height= "25 "> 密&nbsp;&nbsp;码： </td>
  <td>   <input   type= "Password "   name= "txtPassword "   class= "smallInput "   size= "25 "   cTitle= "密码 "   cType= "pwd "   allowEmpty= "false "   id= "txtPassword "   runat= "server "   tabindex= "2 "   maxlength= "20 "   onkeydown   = "keyDown(); "/> </td>
                            </tr>
                            </table>