If you have not yet seen this year's challenge, watch this video introducing it. The challenge contains many different parts, and more rules and intricacies of the game can be found in the full manual.
If you would like a video tour of the field, watch the FIRST playlist (linked below) where official FIRST personnel go through the various field elements. These videos will only cover aspects of the field and not the rules. Thus, make sure you read the maunal!