Can you tell me how over breathing or rapidly breathing increases the amount of oxygen in your body?

No increase in oxyge. Rapid breathing and over-breathing gets rid of CO2 in your lungs but does not truly elevate or increase the amount of oxygen in your blood. An elevation in CO2 is what makes us feel in need of breathing. By lowering CO2 it will take longer for that person to feel the urge of taking a breath and will have the sense of being able to hold the breath longer such as in breath-hold diving.