Purchase a Fitbit Flex. Set up your tracker at fitbit com setup and download the Fitbit mobile app. To open the bracelet, press down toward the bottom of the square-shaped clasp. Insert the tracker into your accessory to track your steps, distance, calories burned and more. Double tap the accessory to show your progress against your goals. Sync your stats to Fitbit’s online and mobile tools – simply hold the accessory near your phone or computer.