First of all, buy a pumpkin in the fruit shop. Then, take a knife and cut a circle at the top of the pumpkin. After that, take a spoon and empty the inside. Put the meat in a bag and freeze it.
Draw the eyes and the mouth lines and cut them.
If you want, you can decorate it with hats, spiders, hair...
To finish, introduce a candle inside and switch it on. You have your Jack O´Lantern. Enyoy it!