Topic..Unlocking the Fireteam extra missions..

I was wondering if anybogy knows how to unlock all the extra fireteam missions. I got the strongehold for free when I bought my game at best buy. I think you can unlock the first 2 on the web site doing that test but I have the second one so any ideas on how to get the rest. I really enjoy the game, it is very tough as I die alot, and sometimes it's hard to see the guys but that is really how it is. Being an ex-U.S Marine they did an outstanding job recreating the look and feel.