Hello and welcome to the monastery.
It seems you are at the very beginning of your learning path... some tip for you:

1)Perl is normally not installed in ms Os. that's incredible but is true. you'll need a distro of Perl for your os: consider as better choice (in my opinion) Strawberry Perl or even activeperl

2)then you have to verify the default association of program in your system: if you have a 'HelloWorld.pl' and when you open it pop-up a text editor it means that the default program id that text editor.

3)if you have Perl installed you must to be able to launch the command 'perl -V' at bottom of the output you'll find wher your Perl is..

4)if you have Perl installed but not associated as default for '.pl' files you are able to run 'perl c:\path\to\yourhelloworld.pl'

consider also to read something like this or that

HtH
L*