Thank you for your question.
The skin around the genitals is naturally darker in both dark skinned and fair skinned people. I'm not aware of any lightening treatments for the genitals. I would be reluctant to try them as the skin of the genitals is quite delicate and sensitive. Most lightening agents used for facial skin contain bleach or glycolic acid which burns the surface layers stimulating younger skin to come to the surface. This is not permanent and needs repeating several times. I would be very worried if someone came to show me such burns because I really don't know how it can heal without further pigmentation or scarring making things worse than before.
You may wish to consult a doctor specialising in skin and DVD for further information about any new treatments available in the market and take it from there. That way at least you would have a good idea of what can be done and how much it might cost.