Complex sentence: He was the co-host of "Good Day New York"; before being premoted to the 6 pm and 10 o clock news previously, he was the co-host of "Fox and Friends" and a White House correspondent for Fox News.
Split into simpler sentences: He was the co-host of "Good Day New York"; before being promoted to the 6 pm and 10 o clock news. Previously, he was the co-host of "Fox and Friends" and a White House correspondent for Fox News.