No reseni je jednoduche pokud vypisujes textak tak na to je treba toto

<?php
$naka_promenna_textak_cesta = "www/".$_GET['neco'].".txt";
$obsah = file($naka_promenna_textak_cesta);
//a pak treba 
$i = 0;
While (count($obsah) > $i) {
echo $obsah[$i]."<br>";
$i++;
}
// potom to lze takto 

$data = ereg_replace("(\<)([bB][rR](\>)","\n",$data);
?>
-----------zde mas <form ... >--------------------------------------------

<textarea cols="1" rows="1" name="xxxx" >
<?php echo $data; ?>
</textarea>