You can run code in external files using require or do, but it's almost always a better idea to use a module for this sort of thing. Don't worry -- making modules is not hard at all. See perlmod.
Comment on Re: calling a perl file from a perl script
You know, I'm not sure I would send someone to that who just said he's new to Perl. It is lengthy, relates almost entirely to package namespaces with very little discussion of how to actually create a module, and is a great deal more technical than would be required to get started.