# this is a complete fragment but not an application. It should 
# start with 'use strict; use warnings' and proceed to set up your
# needed support for file names, variables to interpolate in the
# substitutions, etc.

my %repples = {
    'TITLE' => 'An Exercise',
    'STUFF' => 'Contents of my Pack',
    };

my $keyalt = join '|', keys %repples;
# 'STUFF|TITLE'  *may* be the value of $keyalt, the order might differ

open TEMPLATE, "< template.html" or die $!;
open FINISHED, "> finished.html" or die $!;

while (<TEMPLATE>) {
    s/\*{4}($keyalt)\*{4}/$repples{$1}/g;
    print FINISHED;
}

close(FINISHED) or die $!;
close(TEMPLATE) or die $!;