Okay, latest update:

Apparently, I now have three Perl versions. There's one in my user folder, which knows SDL but not GD, one ActivePerl which knows GD but not SDL, and one default Perl which doesn't know anything. The one in my user folder also has the distinct disadvantage of not being available to other users. This is not ideal. My questions at this time:

1. Is there any way to unite the Perls?
2. If not, is there a way to make the one in my user folder available for all users? Or, failing that, for one other user? Can I just copy it? I'd rather not, since all these Perl versions are starting to fill up my hard drive, but if that's the only way.
3. How do I get ActivePerl to use SDL?
4. How do I get plain Perl to use GD?
5. After I download a package and install it, does that mean I can throw away the downloaded stuff?
6. How do I get rid of the Bash errors?

Come to think of it, I don't know if GD or SDL is what I need. I just want to be able to make a simple GUI. Windows, buttons, that sort of thing. What module should I be using, anyway? Or maybe I should start a different node for that...

Anyway, thank you for your patience, dear monks.