Where do I sign up for kickboxing cles?

are you serious? Any gym in your area will offer this. Most of the time they'll be free to retain membership in the gym. So just stop by any gym, I guaranteed you that you can go wrong just make sure you sign up for a good gym. Try it out a few weeks, than if you like the cles go for a more specialize gym that only teachese boxing or kickboxing cles, also try to martial arts studios.