Custom Pizza Builder

I am very new to web development and had more of a general question. I saw the custom pizza builder on the Papa John's website and am wondering, what goes into building something like that? What language would you use to create it and how would you go about doing it? Basically, in the simulator, you can choose various toppings, sauces, etc. and as you choose them they appear smoothly on the pizza. I'd like to know how that could be accomplished and what language I should go about learning to get to that level. All I know as far as web development goes is basic html and css.