If you did not connect your own domain or assign the site address to a Tilda subdomain when you published your website, you will receive a link similar to this: http://project243352.tilda.ws/page931264.html. It will work, and you can publish it on Facebook. It does not look very attractive, however.
You can assign an attractive, free website address to a Tilda subdomain in Settings. The result will look like this: http://mylovelysite.tilda.ws