I would recommend looking at Dancer. Here is a nice tutorial.

It's very well documented, and there are Advent calendars for 2010, 2011 and 2012, with a lot of knowledge to learn from.

Simple session management can be found here, in a tiny blog engine tutorial.

And, (update), since you want to invest in a good, modern book on Perl, allow me to recommend Beginning Perl (2012) by Ovid. It's fairly recent, it will improve your Perl skills, it covers a large variety of topics, and, within its 700 pages, you will find about 70 on web development, with a good explanation of session management basics.

regards,
Luke Jefferson