For editing RSS by hand (which is not too hard):
This line goes into the head part of every HTML page to detect your RSS feed:
<link rel="alternate" type="application/rss+xml" title="Feed" href="feed.xml">
The RSS file is a simple text file (in my example, it's called "feed.xml"). In your HTML code, link to the RSS file like you would link to an image on your page. As I have the RSS file and the HTML pages in one directory, I can link directly to it without needing to specify any further directories (see under "href", there is just the file name of the RSS file).
The feed.xml looks like this:
<?xml version="1.0" encoding="ISO-8859-1"?>
<rss version="2.0">
<channel>
<title>Goose Attack Feed</title>
<link>http://goose-attacks.at/</link>
<description>New geese attack information on this feed!</description>
<language>de-de</language>
<copyright>Gans</copyright>
<pubDate>20.04.21</pubDate>
<item>
<title>New old scrap!</title>
<category>Tech</category>
<description>Lots of new scrap available!</description>
<link>scrapyard.htm</link>
<author>Gans</author>
<guid>scrapyard.htm</guid>
<pubDate>01.12.22</pubDate>
</item>
</channel>
</rss>
When you have something new to present, you just copy one block between the <item>-tags and alter all the things. That's not the automated professional way, but if you're just using it, let's say, monthly, it's not that much work.