该如何实现... 急..

<html>
<head >
<title>Untitled Page</title>    <script type="text/javascript">    function GoTo(url)
    {
       window.frames["mainFrame"].location=url;
        
    }
    </script></head>
<body>
        <table border="0" cellpadding="0" cellspacing="0" style="width: 1000px; margin:0px; ">
            <tr>
                <td style="height:50px; width: 100%;">
  <a href="JavaScript:GoTo('d.html')">a</a>
                 
                </td>
           </tr>
             <tr>
                <td style="height:50px; width: 100%;">
<iframe id="topFrame"  title="topFrame" frameborder="0" name="mainFrame" src="b.html"></iframe>
                 
                </td>
           </tr>
            <tr>
                <td style="height:50px; width: 100%;">
<iframe id="mainFrame"  title="mainFrame" frameborder="0" name="mainFrame" src="c.html"></iframe>
                 
                </td>
           </tr>
</table>
  
</body>
</html>
是这个么?