Product Pages customization

How would i go about changing the numbers at the top and bottom of the product pages to letters?

Instead of my customers going from page 1 to page 2, I would like for them to be able to see my products alphabetically(A,B,C,D).

Where in the template editor can i find and edit this and how can i edit it exactly?

My wesbite sells flags and it would be a better method to do it alphabetically.

Thanks and looking forward to replies