Press the big green checkmark button on the first page. It may take multiple clicks to play. Then, feed or water your puppy by tapping the bowls down in the left hand corner. Keep doing this and soon you'll have a full grown puppy!
I used a F2U poodle pixel art from Deviantart (https://www.deviantart.com/blusagi/art/40-free-poodle-icons-402004134)