For those about to embark on toilet training, here's both a practical introduction for parents and a read-aloud about two appealing toddlers making the big transition. Photos show infants and children of various races and both sexes; parents are smiling, positive and encouraging. If Mr. Rogers' Going to the Potty is available, this is redundant: Rogers' book covers the same territory but shows a greater variety of toilets and potties, including public toilets.