A debit card is also known as an ATM card. Using this card, you can withdraw funds and make payments using the funds you have in your account.
A credit card is basically a loan that you take. When you swipe a card, say for 100 CAD, it is like a loan. You must repay it on time otherwise they'll levy heavy interest on the sum borrowed.
Most people use a Credit card to pay, not a debit card. Not all debit cards can be used for this.
Try to use a debit card that you have. If you are not successful, ask your bank and get a Credit Card.