They are enemies. The administrator and her assistant, miss Pauling are neutral and they make sure that the teams don't become friends.

Red team: Red Scout Red Pyro Red Soldier Red Demoman Red Heavy Red Engineer Red Medic Red Sniper Red spy

Blu team: Blu Scout Blu Pyro Blu Soldier Blu Demoman Blu Heavy Blu Engineer Blu Medic Blu Sniper Blu spy

Their bases are located in Teufort city that is in New Mexico. Be whoever you want to be.