Make sure you have any available documentation. If you install Perl as outlined earlier, this is already done as part of the general Perl installation, and the instructions that come with your Perl distribution will explain how to get at the documentation on your system. There is also excellent online Internet documentation, which can be found at http://www.perl.com.
First, point your web browser at the main Perl web site, bookmark it, and look around a little, especially at the available documentation. This is an essential resource. Also, point your browser at http://www.ncbi.nlm.nih.gov (the National Center for Biotechnology Information) and http://www.ebi.ac.uk/ (the European Bioinformatics Institute) for two of the biggest government-sponsored bioinformatics resources. These are among the most important web sites for Perl and bioinformatics.
Also very useful is the standard book Programming Perl (now in its third edition). You can do fine with the (free) online documentation, but if you end up doing a lot of Perl programming, Programming Perl (and perhaps a few others) will probably end up on your bookshelf.
Most languages have a standard document set that includes the whole story about the language definition and use. In Perl, this is included with the program as the on-line manual. Although programming manuals often suffer from poor writing, it is best to be prepared to dig into them. A well-honed ability to skim is a great asset. The Perl manual isn't bad; its main problem, that it shares with most manuals, is that all the details are in there, so it can be a bit overwhelming at first. However, the Perl documentation does a decent job of helping the beginner navigate, by means of tutorial documents.