Measure the rice with the rice cooker cup and put it in a strainer. Rinse it under cold running water until the water runs mostly clear. Rinsing is optional but a recommended step in most rice cookers to remove excess starch so the rice doesn't come out sticky.
Cook:
Place the rice inside the rice cooker. Then, add the water. All rice cookers have water lines marked on the side of the bowl. Fill the water to the line that equals the number of plastic cups you added. For example, 3 measured cups = water line 3.
Put the lid on and set it to cook white rice. Some rice cookers have different cooking programs while others simply have a start button.
When the rice is done cooking, remove the lid, let some of the steam vent out, and use a plastic spatula to fluff the rice and serve it.
Notes
All rice cookers use a universal plastic cup. This cup fits ¾ cup of dry rice (190g) and 6oz or ¾ cup (180 ml) of water.
Yield: each plastic cup filled with dry rice (¾ cup, 190 g) yields approximately 2 cups of cooked rice.
Servings: each plastic (rice cooker) cup of dry rice you measure is enough for 2 servings (2 people).
Ratio: 1 rice cooker cup filled with rice to 1 water line inside the rice cooker.
Lost cup: use regular measuring cups to measure ¾ cup dry rice (190g) for each "plastic cup" you want to cook. Then, fill according to the lines inside the rice cooker.