A Product is just a collection of “Files” and “Emails”.
So if you are running a subscription site on “How To Train Dogs”, you could give your product the same name - “How to Train Dogs”.
For every new “subscription” based product you wish to sell and manage using DAP, you need to create a new “Product” within DAP.
You can add both “Files” (basically links) as well as “Emails” to an existing Product.
Adding files means that as an admin, you can say which files on your web site are part of this product, and you can go into each link and specify the access control for that file (is that file free or paid, when is it accessible to the user and for how long, etc). You can add files from your web site using the provided file browser within the “Manage Products” page, or you can also add using full URL’s (like http://www.YourSite.com/dogtraining/protect-this-post.html).
Adding emails means you can setup an email autoresponse to be a part of this Product, and that email can be configured to go out to the user after “X” number of days after she has joined, or on a specific date (in case your email is date- or time- sensitive.