Hmmm... several of my old links for this sort of info
have gone bad.
Here are some that are still good:
the Perl/TK FAQ,
tutorial which is part of
larger repository of Perl/TK stuff.
As jeffa mentions, there is the widget demo that comes
with your TK installation. But there is also a copious
collection (over 90 separate files) of other docs on various
pieces of the TK collection of tools. These are all available
with the Windows install as they are on Linux. On the
I have at hand at the moment
( with ActiveState Perl), those files
are found as HTML in C:\Perl\html\site\lib\Tk and
as pods in C:\Perl\site\lib\Tk. YMMV