Most CMS/blog apps have it built in. You might need to look up how to enable it (Drupal) or you might already have it enabled, even if you don't realize it (Wordpress). Check the documentation for your blogging/site content framework of choice.
If you're super old school and do an actual manual HTML site, just create the RSS file and add entries to it, then link to it. This is well documented and not in any way complex. It's just a text file, after all.
> If you're super old school and do an actual manual HTML site, just create the RSS file and add entries to it, then link to it.
Make use to add an <link rel="alternate" type="application/rss+xml" href="feed.rss"> element and not just a normal hyperlink so that users can just paste your blog URL into their feed reader to subscribe without having to search for the feed link. Ideally this should be present in the page for both the index as well as every article.
If you're super old school and do an actual manual HTML site, just create the RSS file and add entries to it, then link to it. This is well documented and not in any way complex. It's just a text file, after all.