The mission defines the victory conditions and the initial setup of the game. Pay close attention to the briefing screen since it gives valuable information on how to win the game.
This shows the minimum and maximum level players may have to join this game.
This is the speed of the game. It shows the amount of time between each 'turn'. For example, at 60 sec/turn, your fleet will gain flight time each 60 seconds... If you play to play the game only once per day, join game with a speed of 30 min/turn or slower. Turns accumulates when you're not already in the game to play them.
This is the list of the players already in the game. It shows their logo, name, level, character and alliance.
Clicking the join button at the bottom bring a confirmation screen where you can select a new logo and color. This will also be where the game asks for a password if the game is a private game.