The ever-helpful The Brasse has an article on how fellowship maneuvers work, complete with a colorful fellowship maneuvers chart. Which would probably be very helpful if you played in a well organized guild group.
In pickup groups I never got past "everybody click red" in fellowship maneuvers. And even then you rarely get all group members reacting to it. Which is a pity, because if you mastered them, your group could do some really awesome moves with those fellowship maneuvers. Besides damaging the opponent with red, restoring lots of power to everybody with the blue circles seems to be a good move for long boss fights. Now I just need a group with a burglar and people patient enough to try to master all this.