How to Enlarge the Coupon code area

[olumytee4real]

Hi,
Pls i urgently need some assistance. I have a set of digital products that can only be purchased via the use of scratch card pin numbers. This is the only payment method for this site. How do i create a scratch card pin text field where users can type in their pin numbers as mode of payment and this is automatically deduted from the total cost.
Similarly, how do i enlarge the Coupon code text field and also change the save button to 'pay now'. Am sure this would also serve the same purpose though i would have preferred the coupon code field to be one of the standardized payment means. Thanks.