Complex sentence: She started her career when she played in the musical "Bye Bye Birdie" at the age of thirteen, and knew that she belonged in front of the camera when she played in the CBC Halloween special "Boo" at the age of eighteen.
Split into simpler sentences: She started her career when she played in the musical Bye Bye Birdie at the age of thirteen. And knew that she belonged in front of the camera when she played in the CBC Halloween special "Boo" at the age of eighteen.