Update time zone of the United States-Mexico border

Hello, I'm using the google translator, I apologize if there is a misspelling; I know how to update the time zone (or to do ubuntu) to the border towns of Mexico with the United States and took effect on daylight saving time and yet time has not changed. In border cities, daylight saving time begins the second Sunday in March, and the rest of Mexico, the first Sunday in April. As a reference, put the story that supports this change: http://www.elmananarey.com/diario/noticia/tamaulipas/noticias/adelanta_front... or (in english): http://translate.google.com/translate?js=y&prev=_t&hl=es&ie=UTF-8&layout=1&e...