Give code for keys on blog

Hi,

Im trying to make something so my blog gives keys when clicking a link, no idea how im suppose todo it since there are alot off keys and i want it to show 1 keys when a person click the link (1 click per ip)

Something like this http://www.freemmogamer.com/2009/01/tlbb-pre-closed-beta-key-giveaway.html

Were it says this

GET YOURS! – click here
THERE ARE : 887 KEYS LEFT TO GIVEAWAY

Would appriciate it very much if someone could help me, thanks