Here are the steps for configuring Perl.
TextPad does not have any built in compilers. However, it is easily integrated if you have compilers separately.
This is most advantageous for compilers that don't have (or may not come with) their own integrated development environment.
For example, Java, GNU's C++, Perl and ML all are freely available but these free versions do not come with their own IDE. (Java does provide Forte, but it is rather cumbersome for small to medium program development.)
If you install the Java development kit from Sun first, and then install TextPad, TextPad will be configured automatically to allow editing, compiling, running Java applications and Java applets.
If TextPad and Perl have both been installed, you still need to configure TextPad to use Perl.
The TextPad Help contains the needed information and is the obvious reference to accompany this description.