Secret groups are not searchable via Facebook—that means no one but members (and in some cases, former members) can see the group name, who’s in the group, the group’s description and tags, or stories about the group in Facebook’s newsfeed. Anyone can join, but they have to be invited or added by a member or admin, depending on your group settings.
The next step in the process is to consider the flow and the content people are first drawn to on your website and build an audience along the points of conversation, not just based on time. This is especially helpful for content-heavy sites, or for products that are heavily researched and have longer sales cycles. In a longer sales cycle, you can expect more emotion and authority-building to be involved along the way. How to Make a Post Shareable on Facebook