First of all, don't worry about asking questions that you think are stupid.

Your code has a number of problems:

• The first open call will, AFAIK, always fail because you are chdir()ed to the directory that contains the directory you've just found. So you're trying to write to a file with the same name as a directory. See the section about "the wanted() function" in the File::Find manpage.
• I don't thint the space in "> $dir" is a good idea - do ">$dir" instead.
• What is $file? You only use it once as far as I can see. This is where use warnings; can help you.

Anyway, none of this really helps you solve your problem. I would put the directory listings in a separate directory. Take a look at this code (untested):

use strict; 
use warnings; 
use File::Find;

my $listings_dir = 'c:/listings'; 

find(\&callback, 'c:/tmp'); 

sub callback { 
  my $file = $_; 
 
  # Check to see if $file is a directory
  if (-d $file) {
    # Get a list of all the files in the directory (inefficient)
    # (If you only want the filenames rather than paths as well, 
    # investigate using File::Basename. If you want just the files
    # in a directory, and directories within the directory, 
    # consider putting grep { -f $_ } before the glob. 
    my (@files) = glob($File::Find::dir . "/$_/*"); 

    # Save this list to a file
    open LISTING, ">$listings_dir/list$_.txt"; 
    print LISTING join ("\n", @files); 
    close LISTING; 
  }
}
[download]

Good luck with learning Perl. I strongly recommend learning Perl properly--get yourself a copy of "Learning Perl". Your investment in learning Perl will pay back very quickly.