Nice work! You have begun to learn Perl by writing a complete program which gets input from a user and prints output including a modified version of their input. Yes, there is much more to learn, but you have dipped your toes into the pool. Now you can go out there and start learning about the huge and wild world of Perl programming!
Here are a few links to resources that you can use while learning about Perl and how to use it for your own nefarious purposes.
There are a lot more, but I can’t recall many of the links right now. I may put them up as time goes on.