to display the post, go to the bindings panel and expand the form collection, drag the binding for the html editor instance to the page.
I will make this one as a Comment System attached with their profile pages.
well, if it is a comment system, yes it needs to be stored in a database.
if you do not know how to create this, it is not something i can really teach you through this forum, I would suggest signing up for a premiere ticket where we could work with you in a one on one screen sharing session.