There are two ways you could share your tree. You could create a link to your family tree and post that on Facebook so anyone can view it. You would probably want to make sure the box allowing to edit is not checked so that the tree is read-only. Alternatively if you have a website, you could download a Dynamic HTML file of your family tree and host it on your site. When you post a link to this on Facebook it will be read-only and independent of Family Echo.