The other replies showed how to convert your code to a module, but you also asked

Where should I start researching this?

There is a section of the Monastery devoted to Tutorials. Have a look there, but here is a short list of pointers:

• Object-Oriented-Programming Tutorials, especially, perlmod (not listed on the Tutorials page), and perltoot, etc., at the bottom of the OO list
• The section on Modules-How-to-Create-Install-and-Use
• For a very quick introduction, I still like Dominus' The Very Very Short Tutorial About Modules