The best way to win tournaments is the hardest - you have to get better at chess.
Knowing how a tournament works isn't going to really improve your results, short on stopping yourself from breaking the rules and losing from that.
Judging from your performance in your games, you're still a complete novice to the game, and you have a lot to learn. If you want to win a tournament, start trying to improve seriously, and take the game more than just a game.
In my school chess tournaments I've never placed in the top 3, despite beating some of the placers multiple times before. Obviously this hurts, but today was the final chess tournament before high school.
If I can't even win a middle school tournament, what makes me expect I can win a high school one? So, I would like some details on how these work in high school.