A Private League is a fantasy competition between your friends, family or colleagues. You can only join the closed league if you have an invite code or link.
Private competitions can be created in draft fantasy and classic salary cap fantasy. The league commissioner may choose the points scoring, draft interval, league size, league name and other things, depending on the game.
You don’t have to create a separate team to join a mini league. You simply join with the one that you also compete with in the overall ranking.