Pour a right quantity of olive oil and rub thoroughly on your hair for a period of time, till you think it has been massaged lightly. Wash out the oil using warm water. Rub dish washing liquid into your hair lightly and rinse. Dish washing liquid will work and won't damage your hair.
I recommend using shampoo that has vegetable oil in it and a good conditioner. Do not use dish washing liquid, this will strip your hair of its natural oils and cause your hair to become brittle and dry.