In Tourney Machine tie breakers are used to help set pool standings and seeding brackets from those pool standings. To set your tie breakers go to the General Info page, scroll down and click Set Tie Breakers.
Depending on how you seed your brackets you can set tie breakers at the pool level and/or the division level (Tie Breakers within Pools is the most commonly used). The tie breaker options are sport specific, pick the ones you want and put them in the order you want. When you're done click Save. (See Tie Breakers Explained to know how each tie breaker works)