There are two ways to share your shower site on Facebook.
From inside Facebook, you can share the link to your shower like any other website URL you would share.
Post with the shower URL, or send individually via Facebook Messanger.
You can also use the social share buttons at the bottom of each page, you will see a Facebook icon, and twitter icon, if they are turned on.
Let's make sure they are turned on.
Host Control Panel > Privacy & Sharing
From the Privacy & Sharing page in the Host Control Panel, check the box next to the page or pages where you want to display the social sharing buttons. Then scroll to the bottom of the page and click the “Update Settings” submit button. You don't actually need to use this, it just makes sharing the link from a specific page easier, but you can always just use the link directly.