Using your Fossil Stella Sport ES5106 is a breeze. To operate the chronograph, simply press the buttons on the side of the watch. The top button starts and stops the timer, while the bottom button resets it. When it comes to wearing, make sure the bracelet fits comfortably on your wrist. As for water resistance, it can handle splashes and short swims, but don't wear it for deep - sea diving. To keep your watch in top condition, clean it regularly with a soft, dry cloth. Avoid exposing it to extreme temperatures or harsh chemicals. If you notice any issues with the movement or other functions, it's best to take it to a professional watch repair shop.