A Perl script is just a normal text file, which means that you can edit it using a normal text editor.
The system you are using has several editors available for your use, including vi, pico, and others. Those who are not already familiar with vi should probably use pico, as it has a simpler interface. If you're an emacs user, sorry, our server doesn't have the resources to run it, but we do have other editors which have an emacs emulation mode.
To edit a file using pico, type:
% pico filename |
(Note that the percent sign is your unix command line prompt - you don't have to type it.)
To edit a file using vi, type:
% vi filename |
For other editors, just type the name of the editor followed by the name of the file you wish to edit.
A summary of editor commands appears in Appendix B in the back of these coursenotes, just in case you need them.
Incidentally, Appendix C contains a guide to pronouncing ASCII characters, especially punctuation. This will help you translate perl into spoken language, for ease of communication with other programmers.