To use the Kettle 1.5 liter, simply fill the kettle with water up to the desired level, plug it in, and press the boil button. Wait for approximately 4 hours for the water to reach the boiling point, and then enjoy hot water for your beverages or recipes. Remember to unplug the kettle after each use and clean it regularly for optimal performance. Avoid overfilling the kettle and always follow safety precautions to prevent accidents.