Swiss

In swiss tournaments, there are a designated number of rounds to play in the tournament, and each round starts when all the games from the previous round ends.  For example, if the Swiss tournament has 7 rounds, then you will play 7 games.

This is different from an Arena tournament where players can immediately queue up the next tournament game whenever your previous match ends.  It's like normal matchmaking but in a pool with the other tournament players.

You can check these out for more information:

https://support.chess.com/article/335-what-are-arena-tournaments

https://support.chess.com/article/758-what-is-a-swiss-tournament

Also, pairings are done by rating and win-loss record in Swiss tournaments. So let's say you're doing a 3 round Swiss tournament with 8 players. The TD (tournament director) will list the 8 players from highest to lowest rating and pair them so the top half play the bottom half in the first round. So if the highest rated got white (I think that's supposed to be a coin flip), then first round pairings would be:

1 vs 5

6 vs 2

3 vs 7

8 vs 4

After that, the winners play winners and losers play losers. Again, each round the players in the same score group are listed by rating, and the top half play the bottom half. Frequently, people will play someone with a different score, if there's an odd number in a particular score group.