i want to know how do i get into the world champions?

i was wondering i just want to go to the world champions in san diego in 2011 but do i have to buy tickets or something please let me know because i really want to go not to participate but to go and watch with my little brother

There are a few ways to get into the World Championships... hopefully your little brother has met one of these criteria, or he will not be competing:

1. Boost your Premier Rating to a very, very high level by doing well in Pokemon Organized Play Premier Events throughout the year.
2. Win a spot in the World Championships by placing well in your country's National Championships.
3. Place well in the Last Chance Qualifier tournament held on-site a day or two before Worlds.

Now, assuming your younger brother has completed one of those criteria and will be competing, and you just want to watch... you can still attend the World Championships, but generally they won't let you observe the matches close up. I think you need to pay a small-ish fee to get in.