Yes you can, you need to check out Include or Require (they are almost simular).
Heres a piece from my script where i do something simular:
require('top.html');
echo "<div id=\"main\">";
if (!isset($_GET['opt']))
{
$_GET['opt']='';
}
# start main "window" content
switch ($_GET['opt'])
{
case 'brackets':
include "brackets.php";
break;
case 'signup':
include "signup.php";
break;
case 'reggame':
include "reggame.php";
break;
case 'logout':
unset($_SESSION['adm']);
unset($_SESSION['name']);
header('Location: index.php');
break;
default:
require "results.php";
break;
}
#end content
echo "<!-- END content -->";
#end main
In my menu i uses links like this:
<a href=\"index.php?opt=brackets&round=1\">Rounds</a>
If you search around this forum you will find several posts about not including filenames or urls like this:
<a href=index.php?file=some_file.*>something</a>
// ----------
include $_GET['file'];
Because then someone can include whatever file they want into your script.