Using your Tissot PR 100 watch is easy. Just wind it up if it's a manual - wind model or let the quartz movement keep accurate time on its own. You can wear it while swimming or doing water - related activities as it's water - resistant up to 100 meters, but don't press the buttons underwater. When it comes to maintenance, keep it clean by wiping it with a soft cloth regularly. Avoid hitting it against hard objects to prevent scratches on the sapphire crystal. If you need to replace the battery, it's best to go to a professional watch repair shop. And remember, store it in a dry place when you're not wearing it to keep it in good condition.