How cloning Works
Researchers take some mature cells, such as skin cells, to use to be cloned. They then take an unfertilized egg from an adult female of the same species and remove the nucleus of the egg. Since The nucleus houses the organism's DNA they replace the old one with the one made from the cells used to clone. After all of this the egg is put into a third animal of that species to grow through cell division into an embryo. Eventually the mother animal gives birth to one of that species that looks like and is a clone to the animal the original cells came from.
Dolly the Sheep on ABC News
Feb 24, 1997 Dolly the Sheep Video ABC News