Iam 16 years old i weigh 140 and my hight is 5'2 iam i over weight ? if so what do i need to do and eat to loose weight?

Just barely: Your bmi is just into the overweight range. The fact that you are so young can play either way. Some would say you'll gain some each year and end up quite obese. Others may say you'll naturally drop the few extra pounds in the next year or so. It's up to you. Don't do anything extreme. Be active(exercise), eat moderately and aim toward veggies, fruit, non-processed, non-junk, non-fatty food. Relax.