Have you studied about binaural beats and isochronic tones. There are free scripts available that will allow you to make them on your computer. http://lunarsight.com brings the frequencies of many different sources together in one location. You will find some overlap. That is because there has not yet been enough research for everyone to agree on.

As for the marketing aspect, 10 years ago, I could have told you exactly what to do. I had 17 websites each making a good bit of money each month. But I gave it up after a severe auto accident. By the time I came back, just this past year, everything had changed, so I am not a good person to give you advice on that part. Keep searching Google. I have been learning many new things since I came back and I have found free or very low cost classes for almost everything I need to learn. It takes effort to find the free ones, they they are out there for almost anything you want to learn.

As for setting a website up, there are addons for Wordpress that allows you to sell digital download. Some of them are free but there is a good chance you might have to pay a little to get exactly what you need. I have never set one up but did some research on it last year. It is not extremely expensive to do it.