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.