Complex sentence: Nelson began his entertainment career in 1949 playing himself in the radio sitcom series, "The Adventures of Ozzie and Harriet", and, in 1952, appeared in his first feature film, "Here Come the Nelsons".
Split into simpler sentences: Nelson began his entertainment career in 1949 playing himself in the radio sitcom series, "The Adventures of Ozzie and Harriet". In 1952, he appeared in his first feature film, "Here Come the Nelsons".