tcl/tk

[Edwin]

Hi,

I'm rather unexperienced in programming, but I am working on that. I am
working a bit with Perl and Perl/Tk. Now I have found some software where I
would like to make some changes to. In this software I have found the
following formats:
.pm and .tcl. Furthermore have I found the socalled tcl/tk toolkit. 

Now I am wondering if the mentioned formats and the tcl/tk toolkit are part
of the Perl language or that I have to learn another scripting language to
write code in tcl/tk?

If anybody can help me out on this one, please do.

Edwin