Cells called melanocytes determine skin color. All races have the same number of these cells. In the melanocytes are structures called melanosomes, which produce the pigment melanin. We basically all have the same skin color, just different amounts of melanin. Melanin is produced to protect the skin from the harmful ultraviolet rays of the sun.
There is no safe way to permanently lighten dark skin. Skin lightening creams, containing chemicals such as hydroquinone, act by "bleaching" the pigment of the skin. They can be of limited value in women with white skin treating conditions such as melasma (abnormal dark pigmentation of the skin). They must be used with care because they can cause skin irritation. People with black skin are not advised to use lightening creams since they can cause a very dramatic and unsightly change of skin color where they have been applied leaving irregular white or dark patches that are hard to conceal.
TeenHealthFX urges you to look at the underlying reasons why you would be interested in lightening your skin color. If you are uncomfortable with the way you look then the issue could be more complicated then the color of your skin.