Setting up Online Price Retrieval

[subscribe307 at verizon.net]

  I installed ActivePerl 5.8 but now when I select Install Price 
retrieval under GnuCash in the All Programs menu I get the following in 
a command line format:

* Check Perl
'perl' is not recognized as an internal or external command,
operable program or batch file.
'perl' is not recognized as an internal or external command,
operable program or batch file.
Did not find a usable perl.
Please install ActivePerl 5.8 (http://www.activestate.com/store/activeperl)
and add the bin directory to your Path environment variable.
An error occurred, see above.

I don't understand the statement "add the bin directory to your Path 
environment variable"  How do I add this?
Thanks for your help,
Mike