/* Assuming you have these following files.

index.php
goma.php

Here is what goma.php looks like:
-------------------------------- */

<div class="content">
<?="You are in goma page!" ?>
</div>

/*
--------------------------------

We wanted to view the contents of goma.php through
this link:
http://mydomain.com/index.php?page=goma


Here's what a SIMPLE index.php looks like.
-------------------------------- */
<html>
<head><title></title>
</head>
<body>
<?

//determine if we have GET value
if ($_GET['page']=="") {
	echo "Welcome to index page!";
} else {
	//include("goma.php");
	include("$_GET[page].php"); //will substitute any values from var 'page' e.g. ?page=xxx -> include("xxx.php")
}

?>
</body>
</html>
/* ---------------------------------

*** NOTE: Just a simple approach if you want to get
things done. You can use case-switch() or a query
from a database will be a good idea without the use
of other external pages (like goma.php) */