It is very simple... all you need is some olive oil and a shower cap.
1- Saturate the hair with olive oil
2- Make sure to rub the oil with your fingers on hair and scalp
3- Comb the hair so there are no knots or dry spots
4- Wrap a shower cap around the hair
5- Wait one hour
6- Then shampoo your hair several times
Let me tell you why this method works and is 100% guaranteed. Lice breathe from an opening at the end of their body; when the oil is applied to the hair, the breathing cavity will get plugged with oil, and they die of suffocation. You may not need to wait one hour but it is a precaution to be sure.
Lice nit (lice eggs) on the other hand cannot be destroyed. Unless you hand pick them, use a special comb for nits, or apply close heat from a blow-dryer, but this method keeps them attached to the hair. There is a simpler way to get rid of them.
The nits hatch within 7 to 10 days, and after hatching they take 8 to 9 days to become adults. So what you will do is use the olive oil treatment ten days later after the first one, this way you make sure none are left behind. Repeat as many times as you feel comfortable, because olive oil also provides shine, and many nutrients to keep hair and scalp healthy.