You'll need a lichess account and join the blockchain chess team (password is "Hive").
https://lichess.org/team/the-blockchain-chess-team
The Saturday tournament hosted by @sam.chess has ended
There's still the Friday tournament by @stayoutoftherz that you can join.
Here is the announcement and details of the Friday tournament.
https://peakd.com/hive-157286/@stayoutoftherz/finally-hivechess-season-21-is-starting-this-friday