Have you talked to the people who gave you the task? They should know about your environment and be able to show you how to run the program.

In short, the following steps should allow you to run the program, but they assume that you are familiar with Windows and directories/filenames:

1. Start cmd.exe , for example by pressing Windows+R and then typing cmd.exe
2. Change to the directory where you have saved the work copy of the script you are trying to modify, for example by typing cd /d C:\Users\kviki_kiki\Desktop\that_directory
3. type perl -w the_script.pl

If the script you are trying to modify is a CGI script, then you will need to look at CGI and read the text about debugging CGI scripts offline. Alternatively, you could also set up a webserver on your machine and run the script through the webserver.