Complex sentence: Quinn (Dianna Agron), who is ending her high school career on top where she wanted to be, helps Puck (Mark Salling) study for the test he needs to pass in order to graduate.
Split into simpler sentences: Quinn (Dianna Agron) reflects that she will be ending her high school life on top, where she wanted to be. She helps Puck (Mark Salling) study for the test he needs to pass in order to graduate.