Haha, seriously. I can't fathom how you could watch both seasons of the show and have that little idea about what's going on.
Worm already answered this, but just to explain further (again, highlight for spoilers): I can understand how you could be confused at the end of the big battle at King's Landing. The way the episode the week before had ended, it made it look like Tywin Lannister (Tyrion---the dwarf's father, and Joffrey's grandfather) was heading out to attack Robb Stark. They wrote it that way in both the movies and the books to make the end of the battle of King's Landing (also known as the Battle of Blackwater) more of a surprise. Basically, Tywin ended up abandoning his position and leaving his own lands open to attack to ensure that the capital wasn't taken, and that his grandson Joffrey didn't end up getting deposed (along with his daughter---the Queen---his son the dwarf and his two other grandkids getting killed). The other big surprise is that one of the other most powerful families in the series (the Tyrells) who'd previously been allied with Renly (Joffrey's "uncle" and Stannis's little brother) ended up joining up with the Lannisters and were part of Tywin Lannister's forces when he drove Stannis away from King's Landing. And to seal that alliance, Margery Tyrell (the brunette who used to be married to Renly) replaced Sansa Stark as Joffrey's bride to be. She'll be a major character in the show starting next season, and her family will play a big part in the overall story.
