<form action="b.php">
<input type="text" name="userName">
<input type="text" name="email">
<input type="submit">
</form>
<?
if($_GET['userName']!='' and $_GET['email']!=''){
$string=$_GET['userName']." => ".$_GET['email']."\n";
$handle=fopen($FILENAME,'a');
fwrite($handle, $string);
}
?>