Bring the water to a boil (without letting much of it boil away).
Add the rice, and a bit of salt if you like. Cover and boil without stirring for 20 minutes for white rice, 40 minutes for brown rice.
Remove from heat and check that the rice is soft. (You can add some more boiling water and keep checking periodically if it's not.)
Or, get a rice cooker. They heat a metal container for the rice and water, and they let the steam escape. When the container starts to get hot, because there isn't any water left to absorb the heat and escape as steam, the rice cooker turns itself off. (Or at least this is how we think they work.) It's almost impossible to burn the rice, although you can get gooey rice by adding too much water or non-soft rice by not adding enough water.