That's like asking "how can I make a real car out of matchsticks". The answer is, "you can't". Unless perhaps you just use Paypal and static HTML, but you won't be able to store any data other than what Paypal provides.
To make a real online payment system you need a bunch of things:
1) Paypal or a real credit card Merchant Account
2) A dynamic web language like ColdFusion, PHP, JSP, or ASP.
3) That connects to a database like MySQL or SQL Server.
4) A web hosting provider, unless you maintain your own server.
Someone to code it for you.