# first the indentation does not help you read this. 
# we indent to help identify blocks of code like:

if ($this) {
    # do stuff
}
else {
    # do other stuff
}
# end of the if then else
# so we are back at left margin

#!/usr/bin/perl -w  <- good
     use strict;    <- good

        my $dir = "c:/Xwords/";
        my $n=length "c:/Xwords/"; # confusing why use $n why not $length 
                                   # also why not length $dir
                                   # that is what you want afterall
                                   # why type you dir twice: laziness and typos 
        my $from = '.puz';
        my $to   = 'A.puz';
        my $newdir = "c:/Xwords/PrintedXwords/";
        
        while (<$dir*$from>) {                  
        my ($old,$new,$full);               
        $old = $full = $_;              # see how I coded this
        $new = $old =  substr $_,$n;    # it is the same but cleaner
        $new =~ s/$from$/$to/;                  
        
        # you have not coded anything so why the two blank lines
        print " \n \n";
        # if you put in a leading space you get...
        # if you and blank lines do this print "\n\n....
        print " full name of original file is $full \n";
        print " name of original file is $old \n";
        # you don't need the . to concatenate in a string
        # you just need "$newdir$new". also { are literals
        print " full name of new file is {$newdir.$new} \n";
        # if you want 3 blank lines go  \n\n\n"
        print " \n \n";
        
        # this need to be written as I did with no curlies
        # curlies are block delilimiters
        # you should check if this suceeds or fails as demonstrated
        # above with the or die "message $!" the message lets you 
        # say why you have died and $! if the Oh f@#$ varibale
        # where perl puts the error message. The die alone just 
        # gives a line number
        rename $full, {$newdir.$new};
     }

# I have added a counter that will register if all goes to plan
# this will always give you a cheery message regardless!
print "Files renamed !";