Contests are an important part of your event setup, every participant should be assigned to a Contest and if using Splits for timing then these are defined for each Contest.
A Contest is usually described as a group of participants who are all competing on the same course, at the same time (multiple wave starts are still considered the same time), and who should be ranked against each other.

Contests can be added and deleted in the left hand menu.
Each Contest must have an ID, which is a unique identifier for each Contest, and a Name. You can additionally define an abbreviated name, the Contest length, and the scheduled start time.
If you wish to limit a Contest to a specific gender or by age then you can define the eligibility using the Gender, Min DoB, and Max Dob fields. These settings will be used by registration forms to check participant eligibility and adding a participant manually will give a warning if the participant is ineligible.
The Times section allows you to define how times should be rounded and the default formatting which should be used when displaying times. The Start and Finish results are used as part of the scoring and normally only need to be modified if you are using a non-standard format.