use HTML::Template;

my $file = '/path/to/example.tmpl';
my $template = HTML::Template->new( filename => $file );
 
# do all the work to create the content
my $content = "Start of Content";
# ...

# pass content to the template
$template->param( CONTENT => $content );
 
print "Content-Type: text/html\n\n";
print $template->output;