The 10% off is automatically computed into the current exchange rate our processor provides us with.
So you won't get any visual confirmations like you would with a traditional discount (like when you see the breakdown of coupon codes and/or the discount you get when you pay by check or money order).
For Example: So say that BTC is currently $10,000 for 1 BTC. Our exchange rate for BTC would show that the current exchange rate for BTC was $9,000.
When you checkout with BTC, on the last page, you will see the current exchange rate for BTC with the -10% already applied.
The exchange rate is only visible after you have accepted the terms and conditions and processed your order. After you checkout, you will be taken to a page with all the BTC information you will need to complete your purchase.
The exchange rate will show like this: