This is a technique that works thanks to the experience, trial and error, and your business relationship with others in the same medium, definitely something that comes with time and work, but it is highly profitable and if you want everything you need you can find it on the Internet. A practical example would be a book (that you write, pay for someone to write it on your behalf or have sales rights) this text would have some requirements: which is in format electronic (the most common format is Adobe Acrobat Reader or PDF) that have demand, whether in a sector very specific (Golf, medicine, mountaineering, etc.) that is of general interest (health(, Beauty, overcoming Personal and business) you have to buy a domain, host a page, write the text of sale and set up a system of payment, usually through credit cards. Then you faced the problem of Marketing, bring visitors to your site, promotions, guarantees nothing easy if just these dabbling in online business. Sell own products on the Internet requires more advanced knowledge, however, you can start selling products of other people by a Commission, since it does not require much knowledge and can start very fast, the responsibility of the billing, support and warranties, is directly from the company that you promote. That is why I recommend you approaches the sale of third-party products, commonly called affiliated products (products that offer a Commission by referring a new customer) is very important to find products that make you feel good at promoting them. With this I want to say before promoting a product as indicated is that you use it or read, judging whether it works or not for you and for others. This will significantly increase your chance of success. The foundations of a system of affiliates are: these systems operate and produce millionaires that outweigh the problem of Marketing.