My first experience + multiplayer question

So i got Halo Flashpoint through my LGS and a few friends and i played the 2v2 tutorial and i played a 5v5 slayer game with no respawns or any other pick ups and I have to say, i had a blast playing it.

My friends and I wanted to play a 4 player game but i didnt seem to see any rules in the book for it so how does everyone else do a multiplayer game?