You don't need to publish anything if you don't want to. If you choose to keep an event or article just for your group to see (for instance in an email newsletter which you send out), it will not go on the community website.
However , if you do publish a story (an event or announcement), and your organisation is a member of a community, it should usually get immediately published on the community website.
However each community has administrators, which may be in-house at interests.me, or community volunteers. This means not everything will always get published, but if it is relevant and interesting to the local community, it should be seen.