If it's simplicity you want, just make this the last line of your script:

<STDIN>;
[download]

This early in your lessons it is probably sufficient to say that this tells perl to wait for something to be typed, and that will have the effect of holding the window open for you. When you have finished admiring your output, just hit Enter, thereby giving the program some input and the window will close. There are lots of other ways to do what you want, like use one of many GUI toolkits or IDEs, but this is certainly simple and cheap!

Besides, I think you may find after some time that despite the shell being "old fashioned", it is often a far better environment to work in!