Write text on image as display as image - php

Question

I have one image in php like this
Now I want to write Number on white textfield at a run time. And then I want to display it as a single image. How I can do this ?
I tried to search over and found different result but none of them worked for me.
I tried http://blog.doh.ms/2008/02/12/adding-text-to-images-in-real-time-with-php/
And this http://php.about.com/od/phpfunctions/g/imagestring_php.htm
It displays something like this that I didn't understand.
"‰PNG IHDR‚2ª‘ËPLTEÿA£vIDAT(‘c`Ø?óþaà1#a“æmcŠ06 ‹cˆ$ngï1ÀPc 6çï†Ä=gŽ¥å²1ó60$n¸
‘cØÀØp.R!‚¡Fhα sl€v5oøð¡Æ&ê •#ÓÀI›Å1U•/LIEND®B`‚"
I am not sure why this is happening . Am I missing something ?
UPDATE
I did this
php opened
$string = "BSThakrar";
$image = ImageCreateFromJPEG("images/temp.jpg");
$cor = imagecolorallocate($image, 0, 0, 0);
imagestring($image,5,126,22,urldecode($string),$cor);
header('Content-type: image/jpeg');
imagejpeg($image,NULL,100);
php closed.
and it give this output

Answer 1

<?php
$string = "BSThakrar";
$image = imageCreateFromJpeg("image.jpeg");
$cor = imagecolorallocate($image, 0, 0, 0);
imagestring($image,5,126,22,urldecode($string),$cor);
header('Content-type: image/jpeg');
imagejpeg($image,NULL,100);
?>
It has to be a jpg image instead of a png you where trying, also $string can be replaced by the input you want it to have.
if you want to use a png, change to this:
<?php
$string = "BSThakrar";
$image = imageCreateFromPng("image.png");
$cor = imagecolorallocate($image, 0, 0, 0);
imagestring($image,5,126,22,urldecode($string),$cor);
header('Content-type: image/png');
imagepng($image,NULL);
?>