This is how the knot is tied ...

the knot will tie itself again in a few seconds

The knot should look like this when you are done

The bowline is often referred to as the rescue knot, because it will not slip, and therefore cannot tighten around the chest of a person it is looped around. Thus, a bowline can be used to safely haul someone to safety if they have fallen down a cliff or hole. NEVER use two half hitches to rescue someone.