It pretty much depends on how many players you have in your tourney. To make this as simple as possible, I'll use 8 players in my explanation.
In a single-elimination 8 player bracket, the #1 seeded player plays the #8 seed player; #2 plays #7, #3 plays #6 and #4 plays #5.
The winner of 1/8 will play the winner of 4/5. The winner of 2/7 will play the winner of 3/6
For the finals, the winner of 1/8 - 4/5 plays the winner of 2/7 - 3/6.
In bracket play, you want to make sure you have either 4 players, 8 players, 16 players, 32 players (etc.) Brackets grow exponentially, so make sure you have a cut-off ... otherwise, you're going to find yourself giving out lots of first and possibly 2nd round "byes".
Best of luck to you!
Kat ♥
BTW ... there's lots more information on the web ... type in "Bracket Tournaments" in your web browser for additional information.