The puresilva website template fully supports digital products.
A digital product is simply a file (or files) that you sell. Your website visitors can read some information about this file/files, and then make a choice to buy it or not.
If they choose to buy it, they add it to their shopping basket, just like they would for a normal physical product, and pay for it.
After payment is verified, they can login to your website, and download the file(s).
Digital products can be a great source of income if you sell them at fairly low prices (e.g £5 for an e-book) - people are happy to pay for something they could possibly get for free if the price is low enough, and the product good enough.