Using the DeWalt DCH172E2 rotary hammer is a breeze. First, make sure the battery is fully charged. Insert the battery into the tool until you hear a click. You can use the mode selector switch to choose between drill and hammer drill modes depending on your task. For example, if you're just drilling into wood, use the drill mode. If you're working on concrete, switch to the hammer drill mode. When using it, hold the tool firmly with both hands, using the side handle for better control. For safety, always wear appropriate safety gear like goggles and gloves. When you're done, remove the battery to prevent accidental activation. To keep your tool in good shape, clean it regularly with a dry cloth after each use. Avoid using it in wet conditions as it's a cordless tool. If you notice any issues with the motor or the mechanism, stop using it and have it checked by a professional. Also, make sure to store the batteries in a cool, dry place.