Are you wanting to replace your actual site header on these pages? If not, you can just use the Page Header add-on to include a secondary header on the newsletter pages. That would be your best bet.
Otherwise, you’ll have to use the code posted above, and replace the page slugs with the page slugs to your pages. If you’d like to post the URLs to the newsletter pages here, I’ll try to find some time to write something up for you 🙂