Submit articles k2 ?

Giovanni,
I'm not exactly sure what you mean by "send the articles from the frontend of k2". JFBConnect will allow you to import the user's Facebook email, name, email address, gender, and some other info into K2 when the register. Once they're registered, they'll be treated like a standard Joomla user. If you're looking to let users become authors, that'd take a very minor code change to add them to the correct group on registration. If you're looking to have the user's new articles automatically post back to a Facebook Page (or somewhere else like that), that is not possible.

Let me know if that helps, or you have other questions.

Thanks,
Alex