after choose new game in east area, you will see j's bar, but 2d picture, then you need wait for 10 minutes.
only player 1 can control your character, if you want more players, just wait and let them choose different characters.
after beat first scenario, you can save game, then choose next scenario, but random.
if your team cant see you in 2nd scenario lobby, press start button and choose east area again, then choose load game, until your team join lobby. but looks like george only can join the hive and dd, not sure.