Step 1- Make a free blog about the product you are selling using Wordpress or Blogger. Make it look good and stuff it with relevant news articles. Don't put any links in it.
Step 2- Buy a domain name and forward the domain name to your blog.
Step 3- Make your ad on Facebook, and as your url put your forwarded url in there as your link, so when FB officials check it out they get forwareded to a nice blog, so they'll approve it.
Step 4- Once it gets approved forward the domain from the blog to your landing page/directly to the offer.
This works best with health offers because facebook will not approve them as direct links. Good luck!