The 2010 animated film "How to Train Your Dragon" was great fun. So much fun a sequel is in the works for 2014.In the meantime, DreamWorks has turned it into an animated TV show. Dragons: Riders of Berk (8:30 p.m., Cartoon Network) pretty much picks up where the movie left off. Hiccup (Jay Baruchel) and his dragon, Toothless, are joined by the other Viking youngsters and their pet dragons.Judging from the premiere episode, the TV show isn't up to the quality of the movie. (No surprise there.) But it is fun. And it's great to look at.Elsewhere on TV ...Democratic National Convention (8 p.m., Channels 2, 4, 5, 7, CNBC, CNN, C-SPAN, Current FBN, FNC, MSNBC): San Antonio, Texas, mayor Julian Castro delivers the keynote address; first lady Michelle Obama speaks.America's Got Talent (7 p.m. and 9 p.m., NBC/Ch. 5): Twelves acts perform.Hell's Kitchen (7 p.m., Fox/Ch. 13): The final two contestants are determined.MasterChef (8 p.m., Fox/Ch. 13): The final three contestants compete.White Collar (10 p.m., USA): A series of museum heists targets rare artifacts.Covert Affairs (11 p.m., USA): Arthur makes bringing Simon in a top priority.