Once the brackets are published, you and your teammates will get a notification about an upcoming match. To check it out, click the bell in the top-right corner of your screen. Clicking the notification itself takes you to the match page, where you'll see your team and the enemy team.

From there, you can access player profiles and match communication.
When you reach the playoffs, pick-and-ban maps will be available here.

If you don't get a notification or want to check on other matches,
you can see the Upcoming Match Page here