There are many home remedies that can be used for lightening dark skin.
Some of them are here:
1)Grate fresh cucumber and apply the juice on the dark areas of your skin.
2)Rub the inner side of a lemon on your skin with gentle moves, leave it for 20 minutes and then wash yourself with warm water. After that, it would be feneficial to use a moisturizer so your skin doesn t' remain dry.
3)Make a mix of a teaspoon each of milk, honey, and lime juice, rub this into skin and wash after about 30 minutes.
4)Mix gram flour with a pinch of turmeric & a tiny amount of milk. Make a thick paste and apply on your skin. Use a small amount of water to rub it off.
You can find more by visiting this website:
Home Remedies and Natural Cures for Common Illnesses