Chances are that at some point you have considered taking an online course (or perhaps you already have). The process for finding the right course is similar for most people, which goes something like:
1. Open a browser
2. Go to Google
3. Search for “topic” +online course
Naturally, the more popular offerings work their way to the top. The problem with this approach though is that hardly anyone moves past the first page of results. So ultimately you are exposed only to those offerings that have the financial means available to advertise.
Alternatively, you may just go straight to a site that you have used in the past. For example, many people take an online course on Lynda.com. If you have had a good experience before, then it makes sense to go to that site to see if they have a course on the topic you are looking to learn.