Does this mean I have to pay twice?

I bought something online and it had "Billing Address" and "Shipping Address". I know what "Shipping Address" means, but I'm a little confused about "Billing Address". I paid using my debit card, but ordered under the "Credit" selection, since there wasn't one for "Debit". But, shouldn't the order be paid for since, I used my debit card and it takes money from my checking account? Or will I get a bill in the mail saying that I have to pay 'this amount of money'? I'm confused and I hope my question wasn't so confusing or hard to understand.