I have a very yellow complexion. i am "tan". i want a perfect fair white skin.

There's no "perfect": There is no such thing as "perfect" when referring to humans, or to real life in general. Yellow may or may not be normal, depending on one's parents' skin colors (we don't get to choose our parents). Yellow may also be a normal condition called Gilbert's, or it could be a medical problem. Tan is usually normal, especially if one is more tan where the sun shines on the skin and less tan elsewhere.