How do you make debit card transactions?

I'm in a business class and I have a presentation on Firday! I need to explain to every one how to make debit card transactions?|||When you go to the check out to pay for your items with a debit card. After the cashier has total your purchases. Then you say I want to pay with Debit card. She will they type something into the cash register and next you will swipe your card. There is a machine right in front of where you are standing. You swipe your card. Next the machine will say to enter your pin number. That is a number that only you should know and no one else. After you enter your pin number the machine will read "do you want to complete this transaction and you will click ok or sometimes it will say do want cash back. If you do not want to get any extra cash off of your account then you press no. The cash register will receive your informations and if you have enough money in your accout to cover your purchases it will print out a recieipt.Some time in smaller convient stores the cashier will take your card and enter your card number and there is a pad on the counter and it will say for you to enter your pin and press ok. Hope this helps.