Once you have been seeded into a bracket you will get a match notification. Press the Go to Match button on it and you will be taken directly to your match page.
If the organizer has match check-in turned on:
Once you are on your match page you will see an "I'm Ready" button and a timer. Pressing this will set you as ready in the match and alert your opponent that you are ready. If your opponent does not ready up before the timer runs out then the system will automatically give them a loss and move you forward.
Depending on the game, you may be given on page instructions of the steps to take. You may also need to select bans or review other steps at this point. You should follow the onscreen instructions.
Here is an example of what the instructions page will show for Super Smash Bros Ultimate.
Not all games will have these detailed instructions. You should review the rules page on the tournament or contact the organizer of the event if you have any questions on how to proceed.
Once you have finished checking in, being ready in-game, and doing any other tasks like banning or stage selection, you can now go play your game! GL HF and be ready to come back to report your score
Now that you've beat your opponent and taken a screenshot of your victory screen, you will want to click the "Report Score" button on the Match page, then click "Report Score Game 1" and then choose the winner. Repeat this step for each game as necessary. That's it.
Some organizers may require the opponent to confirm the score:
If score confirmation is required, there will be a timer displayed after the score is entered. The player entering the score will have to wait for the opponent to confirm or dispute the score. If the timer runs out, then the score will be accepted automatically. If the opponent disputes, then an issue will be raised automatically for an admin to come to assist.
The system will then move the winner onto the next match and you repeat this process again. If you have a problem anywhere during this time, such as your opponent hitting ready but then not responding to you, score being incorrectly reported, player stalling in the lobby, and other issues; you should press the "Report Match Issue" button. This will notify the admins that there is a problem in this match and they will come to the Match on that page.
It can sometimes take a few minutes for admins to respond depending on how many disputes they are currently handling. During this time you should explain in the match chat what the problem is and provide any screenshots for proof.