Hi there Ian,
There are a couple of ways to do this.
- Visit your Airbnb listing page and copy & paste your listing url to your facebook page.
- Again visit your Airbnb listing page, then scroll down to the box just under save to wish list and there you will find email, messenger and ...more. More gives you numerous ways to share your listing and Facebook is one of them. Once the window opens and you are logged in, if you click share on your timeline you will see the option to share on a page you manage.
A recent update also now allows you to embed your listing onto a website by copying the html code it gives you.