I have the same setup with about 6 different coupon codes!
What you do is follow the proceedure that you did for the first coupon as many times as require....just adding the new details as a new coupon. I'm not at my desk computer so I can't give you the steps and my memory isn't that good. But it can be done with ease.
As I'm not a developer I think from memory I just followed the instructions WA give for setting up one and repeated them as a new coupon for each different one I needed.
Hope this helps