Get tickets and join the crowds at a game at Chungcheng Stadium. If there's nothing on while you're there, you might like to check if there's a tour of the grounds.
You'll find this sporting facility in Lingya District. Once you've explored everything you want to at Chungcheng Stadium, take a look at nearby Lotus Pond, Kaohsiung Museum of Fine Arts, and Former British Consulate at Takao.