Question, do I have to add that if someone get hits by a zombie or die they become a zombie. Also at the beginning of the round do I have to add that certain people become zombies?
It's all done by the ZombieReloaded plugin, but sure if you want to change some settings like amount of first zombies, delay between first infection and some other stuff(use it to balance your map if you don't want to edit the map design), you can do it by entity called point_servercommand i believe.