Once you've met the requirements, talk to Bossman in the lobby and he'll give you a first-time's-free pool of three to four possible recruits you can hire. To start out, you must finish the Contract Mission 'Pilot Episode' at least once before Bossman will be able to gather possible recruits.
This guide applies almost exclusively to Arena Mode, but the Hireling Orders sections also apply to stages of the Story Campaign where you are playing with Deimos and Sanford in singleplayer.
