To use a pressure cooker, first, add the required amount of liquid, usually water, to the cooker. Next, add the food or ingredients to be cooked. Close the lid tightly, and set the pressure level on the vent, depending on the recipe requirements. Place the cooker on the stove over high heat, until it reaches pressure. Reduce the heat to maintain the pressure, and set the timer according to the recipe instructions. After the cooking time, remove the cooker from heat and release the pressure carefully using the pressure release valve. Open the lid when all steam has been released, and enjoy the perfectly cooked meal.