Hiya, i did the same as only got one when i bought it. Programmed mine yesterday using the instructions found here Honda Remote Programing
. Just keep switching it to 2, pressing lock and switching to 1 over and over until you get it working, remember to press the button for at least a second and don't flick the key on and off too fast. Oh yeah, don't forget that when you programme your new remote the old one won't work so you have to do that one at the same time but it tells you how in the link. Hope that helps!!