"I am a biologist and have only started using perl over the past month so am feeling a little lost."

I recommend you bookmark "perl - The Perl 5 language interpreter".

From this page, you'll find links to the documentation for all the built-in functions, modules and other parts of the language as well as FAQs, tutorials and other resources.

Rather than attempting to read everything at once (a particularly daunting endeavour), I suggest you familiarise yourself with the various sections and what they provide: this is a much simpler task and will allow you to quickly access information as and when you need it.

Having said that, you'd probably benefit from reading "perlintro -- a brief introduction and overview of Perl" in its entirety.