How to install Markdown Extra onto Altervista server?

So. I'm currently trying to build a site here, and over at Yahoo Answers, after receiving this helpful advice from Reddit's r/html, I asked a question about how to install Markdown Extra or Parsedown onto my site.

Here's my dilemma: even with all the help I received from the 2 communities, I'm pretty bad at this whole "PHP" thing, as mentioned in the Yahoo Answers question. I tried uploading the files from the .zip file on the PHP Markdown site by Michel Fortin to my website server, hosted here at Altervista. I then used the PHP "include" command on one of my .html pages to link to the "MarkdownExtra.inc.php" file in the containing folder to try to test my sample Markdown code, but to no avail.

I really want to use this language, because I expect that I'll be handing over the keys to the website back-end to other, fairly coding-illiterate people, and I want to make sure that they can still work with it once I'm gone.

So, can you guys show me how I might go about installing Markdown Extra on an Altervista server?

If you can screencast it, that'd be extremely helpful.

Thanks, guys!

P.S. I work independently of WordPress and other CMS systems, in case that helps.

Could you please post the PHP code you are trying to get working?

This is the PHP code I'm trying to get to work. (It's all in a .zip file.)

To be more specific, though, I'm trying to "include" the file "MarkdownExtra.inc.php".

As I said, though, I have little experience with PHP, so I don't know how to implement it onto my site and into my .html files.