The new Software can be downloaded through the dedicated Apple Watch app on the iPhone by going to General --> Software Update. To install the update, the Apple Watch must be placed on the charger and it must be in range of the iPhone.
Watch OS 1.0.1 includes Performance improvements and bug Fixes for Siri, measuring stand activity, calculating calories for indoor cycling and rowing workouts, distance and pace during outdoor walking and running workouts, accessibility, and third-party apps. The Software Update also includes support for new the emojis found in iOS 8.3 and it provides additional language support for Brazilian Portuguese, Danish, Dutch, Swedish, Russian, Thai, and Turkish.