As you will have realized by now, there are many ways to do this with Perl. However as you are migrating from PHP, I would suggest that you would enjoy a smoother transition by using one of Perl's 'code in HTML' frameworks.

There are a number of mature solutions to chose from here e.g. Mason, Apache::ASP or EmbPerl

I'm quite fond of Mason - there's a free book available; e.g. to include your anouncments file, you could just do:

<!-- other HTML -->

<& anouncments.txt &>

<!-- more HTML -->
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