The easy way to find out what seeds wrestle each other in the first match is to add 1 to the bracket size. The seeds of the two wrestlers will always add up to the derived number. e.g. In a 16 man bracket... 1 vs 16, 2 vs 15, 3 vs 14 4 vs 13, etc.
Furthermore, assumming the top seeds win, the second round seed can be determined by dividing the bracket size by 2 and then adding 1. Therefore the second round of a 16 man bracket will have 1 vs 8, 2 vs 7, 3 vs 6 and 4 vs 5.

That's probably more explanation than you wanted. Here's what a 16 man bracket looks like...

Seed 1 vs Seed 16
Seed 9 vs Seed 8
Seed 5 vs Seed 12
Seed 13 vs Seed 4
Seed 3 vs Seed 14
Seed 11 vs Seed 6
Seed 7 vs Seed 10
Seed 15 vs Seed 2