Okay I read post 1 again and I think since you sold you first one, that is why you could not continue.
As per post 1- Once the breeding has finished, you'll be prompted by Freza (a new character!) to jump aboard the Arctic Airship to take the frozen egg to the new world for incubation! Breeding an Ice Age dragon isn't too tough, just combine a purple colored dragon with a Winter Dragon and see what happens!