How to create a community?
1) Once connected, go to "network - Communities".
2) Click on "create a community".
3) Fill in the fields to create your community.
4) Make sure to click on "validate my request" so that your community is created.
Note: It is possible to define different visibility status of a community: public or on acceptance only. When you post content in the community, you decide whether it's visible to everyone, or only by your members or contributors.