Need help to break lines in this script:

Hello, i need help to improve this script, i don't know how to break lines.
When i press "Create" button, if the phrase is too long...they escape from the image.

So i need:

1. break lines
2. Limit the width of phrase and automatic break lines into width of image.

online: http://rflmao.info/

<form method="post">
<textarea name="user" cols="80" rows="5" class="textbox">
Text

It doesn't break

lines
</textarea>
<input type="submit" class="button" value="Create">
<input type="image" border="0" width="500" height="410" src="write.php?caption=<?php echo $_REQUEST['user'] ?>">
</form>

Code (markup):

And the script:

<?php
header("Content-type: image/jpeg");
//$user = $_POST['caption'];
$user = $_GET['caption'];
$im = imagecreatefromjpeg("imagem.jpg");
$user_width = imagettfbbox(9, 3, "tahoma.ttf", $user);
$x_value = (250 - ($user_width[2] + 113));
$color = imagecolorallocate($im, 0, 0, 0);
imagettftext($im, 25, 0, $x_value, 58, $color, "tahoma.ttf", $user);
imagejpeg($im);
imagedestroy($im);
?>

Code (markup):

Any help is welcome, i'm new in php.
Thanks!

 

$text = "The quick brown fox jumped over the lazy dog.";
$newtext = wordwrap($text, 20, "<br />\n");

echo $newtext;

PHP:

http://us2.php.net/manual/en/function.wordwrap.php