During the bullfights, you'll want to hang out in the Sol section. As you've probably guessed, Sol means Sun. These are the cheap seats, and they’re a whole lot of fun. The Pena’s (communal groups) all hang in the Sol Section. They chuck food, splash sangria, sing, play drums, and blow horns for the entire two hours of bullfighting. If you want to actually watch the bullfights, sit in the Sombra (shade). If you want to have the time of your life, sit in Sol. Wear clothing you are prepared to trash afterward. Do not bring any electronics as they’ll be destroyed by Sangria. Also bring food and drink. You’ll need to hydrate, and possibly retaliate.
For more photos of Fiesta de San Fermin, check out Jim Hollander's web site.