The best thing than you can do is to have a page of unloadings simple and to give exactly what you offered at first. If your product can be unloaded (format exe, zip, pdf, doc, etc.) you must include a direct link from your page of unloadings. Also you must include detailed instructions exceeds how the file is due to execute or abrir. Once your page of sales and the one of unloadings are already ready, you must asegurarte that all the system is working correctly. The company realises a fictitious purchase (processor of collections in line must permitirte this option) happening through all the stages of your process of sales for asegurarte that is no error in him.
When you have reunited these 3 aspects (the page of sales, the service of collections in line and the page of unloadings) you will be able to automate your process of sales so that it does not depend on you. The key of this one automatization is in which once a prospectus finds your Web site, it reads your page of sales and it is decided to buy your digital product must in line be directed to the safe servant of your service of collections so that it realises the payment by the exact amount and the chosen product. After approved the payment, the service of collections in line must redirigir to your client to the page of unloadings that you have formed in your account of the service. And this page of unloadings or must count on the information necessary to give to your product or service to your client without you must move a finger. You can be selling your product or service being of vacations and even while you sleep. The unique thing that must worry to you is the attention customized to clients, to respond doubts about your product, etc.