Instructions
Enter the Calm Lands and walk down the slope. Walk northwest until you reach a shopping area.
Wait for your team to finish resting at the shopping area. Continue walking northwest. When you can go no further, head north.
Talk to the woman riding the large, yellow, chicken-like creature looking out over the cliff. She is the Chocobo Trainer. Press "Circle" to speak to her. She will not offer you a chocobo to ride unless you help her tame one. To tame the chocobo, you need to take it through an obstacle course.
Complete the obstacle course by staying within the lines of balloons and crossing the finish line between the chocobo and the trainer, both in under 12.8 seconds. If you succeed, the chocobo is tamed. You are now able to ride wherever you want in the Calm Lands.