Php Text Overlay with user input form


so someone asked me about a website where (very similar to when u get something engraved at you have say a Car number plate that is blank then the user puts the registration number into a form hits submit and a new image is shown with the Reg number overlayed on it.

Ive got the overlay script sorted (well it works)


//PHP's GD class functions can create a variety of output image 
//types, this example creates a jpeg 
header("Content-Type: image/jpeg"); 

//open up the image you want to put text over 
$im = ImageCreateFromGif("template.gif");  

//The numbers are the RGB values of the color you want to use 
$black = ImageColorAllocate($im, 0, 0, 0); 

//The canvas's (0,0) position is the upper left corner 
//So this is how far down and to the right the text should start 
$start_x = 550; 
$start_y = 100; 

//This writes your text on the image in 12 point using verdana.ttf 
//For the type of effects you quoted, you'll want to use a truetype font 
//And not one of GD's built in fonts. Just upload the ttf file from your 
//c: windows fonts directory to your web server to use it. 
Imagettftext($im, 24, 0, $start_x, $start_y, $black, 'verdana.ttf', "Text I want to Appear"); 

//Creates the jpeg image and sends it to the browser 
//100 is the jpeg quality percentage 
Imagejpeg($im, '', 100); 



so its the user entry bit im struggling with really, I know how to make a input box and what not but actually how to link it so that when i hit submit, the php calls that data and displays it on the image

Any pointing in the right direction would be awesome

(i also just realised ive been a member of kirupa for 11 Years lol)