Here are a few things you might find handy:

• My mini-lecture about Perl/Tk, in PS format (compressed). You might find the page size & orientation quite annoying with this file, so
• The Perl example I've cut down to pieces in my mini-lecture.
• you might consider taking the entire LaTeX bundle, including a DVI, and the Perl example. (tar-gz compressed)
• A very recommended pocket reference. Actually, I bought the book from amazon. It was $10
• And here's the Tk package itself for a UNIX machine. Even though my Mandrake 7.02 made noises as if Tk was installed, an easy and quick installation of this package got me on the road.