You can join a community through “Discover and Join” to select a community and then join whether by pressing “Request” in case it’s a private community or “join” in case it’s a public one. Joining a community differs based upon its privacy: In case of public community, you will be able to join the community without waiting for the community admin to accept your join request. In case of private community, you’ll need to send a join request that has to be accepted by the community admin to be able to join. In case of hidden community, you’ll only be able to join upon an invitation sent to you by the community admin.