Simplify the following text for a Grade 9 native English-speaking person.
Original: Edge , who stormed through the ECW crowd , was attacked by Cena , who cost Cena the WWE Championship at ECW 's One Night Stand , and written into the storyline , sought revenge against Edge .
Simplified: Edge , who tried to leave through the ECW crowd , was attacked by Cena , because he caused Cena to lose the WWE Championship at ECW 's One Night Stand , and Cena wanted revenge against Edge .