"Place chicken breast halves in a medium saucepan and add enough water to cover. Bring to a boil over high heat. Reduce heat to medium; simmer 8-10 minutes, until chicken is cooked through. Drain."
Then, you can shred it, cut into cubes, etc as everyone was describing. Now, I do know this: Make sure that it is not pink inside the chicken. After about 8 minutes, take one breast out and make a small slit in it. If it's pink, it needs to cook longer. But, a meat thermometer is the most accurate way and the safest. My guess is that they are talking about 4 chicken breasts. Cook longer for more than that. I don't know if this works for frozen chicken breasts.