OK - I know this is a dumb question, but I want to purchase a ticket for Thanksgiving on UAL and I have a $25 cert I got with my UA credit card and I also have a customer service $150 cert.

I'd like the 1000 mile bonus and to be able to use at least one of these certs.

Anyone have an idea how I can do this - I can't find anywhere to fill in coupon codes etc. on UAL.com. So is it just me, or is there no way to do it?

Thanks!