Thanks for the informative explanation. And it seems the procedure is very simple, though it will take some time.

Many people mainly try to index their website in Google search, as you said it's very simple if we submit our site to google and then add sitemap. But many people complain submitting sitemap does not work with Google. Google always shows some or other errors while submitting sitemap. Do you know any alternatives to Google sitemap to list all our pages to Google?