Working on implementing image descriptions to a php run gallery and can't seem to figure out how to call each text file for each individual image.

   //total number of images
   $total = 77;

   //max number of thumbnails per page
   $max = 9;

   //what image do we want to start from?
   $startcount = $_GET["start"];

   //if there is not a defined starting image, we start with the first
   if(empty($startcount))
    {
   $startcount = 0; 
  }

   //start off the loop at 1
   $loop = 1;


   //start the loop
   while($loop <= $max)
    {

   //for the picture labels
   $num = $startcount + $loop;

   if($num > $total)
    {
     $num = $num - 1;
     break;
    }

   // Add class="last" to every third list item
   if(is_int($num / 3))
    {
     $last = ' class="last"';
    }
   else
    {
     $last = "";
    }

   //the code for the image
   echo '

        <li'.$last.'><a href="images/portfolio/pic-'.$num.'.jpg" rel="milkbox[gall1]"><img src="images/portfolio/thumbs/pic-'.$num.'-thumb.jpg" width="256" height="138" alt="Thumbnail of image '.$num.'" /></a><div>'.$num.'</div></li>';

I see that I can call the text files by number using '.$num.' (I have 77 individual text files with a phrase in each) but how do I tell it to call the files?