How to build an e-commerce website like this?

I am a beginner of the e-commerce part.

I just want to ask how to build a website like the link below:

http://ift.tt/1mT8qVo

Example: When you select right part to "Division IV", then it will show the price $24 at the center, then you click 'Confirm & Pay", it will automatically build an Paypal invoice payment $24.

I want to know that how to do the process of it, just the center part of the website.

I just used some e-commerce template before(like Prestashop), it can automatically build Paypal invoice. Is the website builded by the e-commerce template? And just modify it? Or it is build by themselves, if so, how to do that?

I have main domain and host.

Please help me.

Thanks