Maria, i am Tom and i am also just a customer here and despite there being a lot wrong with some templates and extensions i unfortunately have to agree with Paul's statement.
From all the information here, you failed to match your requirements to the capabilities of the template and then look for an alternative method to implement a membership component. Templates generally don't include this functionality as it is not the task of a template. A template is only how the site layout is created and how the content is styled, it is not about adding functionality beyond reason. This is also not how Joomla works or intends templates to function.
To make things easy, there are components out there, that would implement the functionality you search. In essence you add a group and after payment the person signing up gets assigned to that group. That group then get's access to the content. This is a very basic explanation from a 10,000 feet height, but as i don't have more information, i can't really say more.
Please search for Membership Pro or for RS Membership, or a general search on the Joomla Extension Directory and then look for Membership & Subscriptions. It will give you list of a bunch of extensions you could use. And this time please research of what these components can do and if it includes a payment processor that you can and want to use.
From whatever i know, i can only recommend that you take a couple of days and first nail down your requirements. Write them up, do your research, come back where you can't find a solution, change your requirements and implement workarrounds. In essence creating a web-presence is not that different from creating a business plan or any other project in IT. It starts with gathering ideas, then research, writing down requirements, consultation, more research, an action plan and then you implement to put it very simplistic.