The cool thing about forums is that you have 3426 different ways to store stuff depending on what you want you're forum to do... The basic design of your forum is correct, but you might want to consider opening new files for each of the comments posted. Ie:

# put all posts in ./msgs
open(WRITE,">msgs/$^T.txt") or die();
print WRITE "<P>",$query->param('name');
print WRITE "<P>",$query->param('subject');
print WRITE "<P>",$query->param('message');
close(WRITE);

# ... 

# and later when you're making up the page...
# sort the messages by date
foreach $msg (sort glob('msgs/*.txt')) {
  open(READ,$msg) or warn($!);
  @msg = <READ>;
  close(READ);
  print FORUM "@msg\n";
}
[download]

By doing this, you can later on make is so that each one of you're posters can re-edit his own post, generate stats, clean-up old messages and other cool things of the sort...

Forums were the way that I learned perl in the 1st place. Forums are fun!

#!/home/bbq/bin/perl
# Trust no1!