To design an interactive website, you need:
HTML, Javascript, a server side language, a database, AJAX and very SERIOUS programming knowledge and experience.
Failing that, you can try to download a thousand "free scripts" and/or CMS, and try to adapt them to your needs. This will take you longer than learning to program in all existing languages (without talking of the frustrations and irritations you WILL suffer by not understanding the "WHY" that script does not work...
Failing that, get a freelancer to work for you, but BE PREPARED to pay the price! An interactive website like the one you propose will take some serious programming to do, and experts are not cheap.
You will, surely, get a hundred amateurs to quote you a few hundred dollars, but NONE will supply the goods. Be prepared for several 1000's!