Tomlevell is correct. You play each other player as both black and white. Top 3 in each group go through.
The groups are seeded according to rating. Hence StevoMcD, Me, and Wasnevergreat, the highest graded are in different groups. Groups are here.
https://www.chess.com/tournament/stw-clocks-back-2023/pairings
Gradings? For a detailed explanation you can use google but basically you are graded according to your results against other players. On average if you play someone graded 200 pts higher you can expect to score ).24 . IE if you played 2 games you would lose 1 and draw one. Once the rating difference is 366 the higher player scores 90%. All statistical averages. It can vary according to poayers style of play etc.
After all groups are completed if interested I will do another tournament for the runners up so nobody is going weeks without games if they want to carry on playing. You would then have more players closer to your ability.