Your snippet didn't do anything, so I spruced it up a bit. I'll let you work out the highlighting aspects.

#!/usr/bin/perl

use strict;
use warnings;
use Tk;
use Tk::Wizard;
use Tk::TextHighlight;

my $mw = new MainWindow;
our $wiz;

$wiz = $mw->Wizard(
      -debug => 1,
      -title => 'Wizard',
      -style => 'top',
      -tag_text => 'Wizard',
);

$wiz->addPage (
  sub {
    $wiz->_text_frame(
      -title => 'Highlight',
      -syntax => 'Perl',
      -text   => "Setup Guide",
    );
  }
);

$mw->Label( -text => "MainWindow" )->pack;

my $button = $mw->Button(
    -text    => "Start Wizard",
    -command => sub {
        $wiz->Show();
    }
)->pack();

$mw->Button( -text => 'Quit', 
             -command => sub { exit; } )->pack;

MainLoop;

__END__
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