As a general rule, you can safely assume that any option or setting you don't recognize probably does not concern your needs and can thus be ignored. Instead of trying to get the "big picture" of how the entire system works in minute detail first, just focus on what you want to accomplish and look for ways to do just that.
All of our features and how to configure them are fully documented in our help pages listed here (and we are always working to improve and refine the documentation):
Our Getting Started help page is a good place to begin setting up your E-junkie service:
If you would like to "test drive" our Seller Admin without using a real E-junkie account, you can use the Demo User "Go!" button on our login page:
(bear in mind you can't use the Demo User login and your own account login at the same time in the same browser).
If you would like to test your setup, you can temporarily set your product price to 0.00, or you can create a secret Cart Discount code that discounts 100% the Item Total and enter that code in the cart you are testing on your site. When the cart total is 0.00, you will be able to use a Free Checkout option to test the process. If you need to test a live checkout including an actual payment with PayPal, then you will need to borrow someone else's PayPal account or have them test your cart for you, since PayPal will not allow you to "pay yourself".
Once PayPal (or any other payment processor you choose to accept) informs our system of a completed payment, we automatically grant the buyer access to a thank-you page offering their download link(s), and we send them a thank-you email with a link to their thank-you/download page, in case they did not proceed there directly after checkout.
We do not offer realtime live support over the phone or otherwise, but if you require that, we can refer you to the services of Andrew at http://www.EasyE-junkie.com/ -- an independent firm that offers video tutorials, training and live walkthrough guidance for using E-junkie.