How to use the content as SEO strategy

Hello,

I want to use the content that users will generate from interacting with my site and my community build around easysocial, but i want to keep it private.

I mean i need that the content can be see it in order to see visible for SEO, i mean for search engines robots specially Google, but that the interaction with that content is just possible to registered members..

How can i set this in my admin configuration?

Thanks!