Complex sentence: On June 20,2008 Rihanna was a guest on NBC's "Today Concert Series" at Rockfeller Center in New York City, performing "Don't Stop the Music", "Umbrella" and "Take a Bow".
Split into simpler sentences: On June 20,2008, Rihanna was a guest on NBC's "Today Concert Series" held at the Rockfeller Center in New York City. She performed "Don't Stop the Music", together with "Umbrella" and "Take a Bow".