welcome to HealthcareMagic forum,
You seems to be getting tanning on face.Use a broad spectrum sunscreen (medicated) allover the face 3 time in a day.
You can use creams like glycolic acid
etc to lighten the color.
You should also take chemical peels
from a dermatologist
which would help you further.
There are lasers also available which can lighten up the color,but the cost would be pretty high.So meet a dermatologist who can offer your above options .