Adam Maslanka

So I'm a bit new to this, at the moment in Spartan ops I seem to only be able to play with other players in episode 4 but in no others. It is a bit annoyingly to be playing alone as I had to save up for the game and it looks like I have to play through alone till I catch up??? Any suggestions would be helpful. Oh and a manual would of been nice aswell. ..lol