How to work a credit card machine
Input the credit card numbers. If you have the credit card in hand, swipe it through the card reader. Most readers have a small icon or picture on them that shows which way the magnetic strip on the back of the card should be facing. If not, try running it through the reader with the strip facing the machine first, since that is the most common direction. If you have a phone order, or do not have the credit card in hand, select the button marked "sale." On many machines this is also the "1" key, but it varies depending on the brand of the machine. Then follow the on-screen prompts to enter the card number and expiration date. Always double-check the numbers before pushing enter.
Input the sale information. Typically, the machine will first ask for the sales amount in dollars and cents. Input the amount using the number keypad. Double-check the amount to make sure it appears correctly on the screen and if it does, then push enter. If you accidentally input the
wrong amount, look for the "clear" or "delete" key and start over. In some cases, the machine will prompt you for additional information after you've entered the sale amount. Follow the prompts to enter information, such as the customer's zip code or an order number.
Wait for the sale to process. Depending on the machine's connection the sale may process within seconds or it may take a few minutes. If the machine seems to become "stuck" while processing a sale, do not re-enter the sale, but instead call the processing company's phone number for further instructions. In many cases this number will appear on a sticker on the machine.
Process the receipt. If the customer is present, have them sign the credit card receipt. Give them the copy and retain the original for your records. If the customer is not present, write "phone-in" or another appropriate phrase on the signature line of the receipt. Keep one receipt for your records and include the other in the shipment of the goods to the customer.Source: www.ehow.co.uk