json php iOS help :(

i want help to end my graduation project ..

we have this code in php (shopping cart) and we wanna to convert it to json to use it in IOs app ,we wanna json to add product to cart, also we wanna json to get the cart info(view Shopping Cart), So help me , i don't know how to convert it :(

http://www.mediafire.com/download/bc63u4c66wvqn6k/cartt.php thats our code. please,help us :)