How to reload the div using ajax

[eluser]JasmineFlower[/eluser]
hi,

I need to reload the below div within the time interval ,how to do this in ajax

the below code displays the folder files in html page.

Code:

<div id="ajaxusing">
&lt;?php  

$dir="../skycad/fence/Fence01";
if(is_dir($dir))
{
if ($handle = opendir($dir))
{
  while (false !== ($file = readdir($handle)))
  {  
     if ($file != "." && $file != "..")
     {  
       echo "<ahref= \" ../skycad/fence/popup.php?filename=$file \"  >". $file." </a>";        
     }  
  }
  closedir($handle);  
}
}
?&gt;
</div>