Earning by comments will require you to have your own Blogs and Websites. You will then share these dedicated domains (Owned by You) in the comment window. If an option to add your URL or website is not available, then you do not include links. You contact the site support first and get permission to share your URL. Oh, and NEVER share affiliate links in comments.
How much will you make? I think my best month with Google AdSense was almost $5,000 over the last ten years. That amazing month blew my mind since it was actually near the beginning of my blogging journey. When you go from making zero to $5,000 in a month, that will rock your world. For me, it also got me even more excited because I knew there were other ways to monetize.