SolvedPB Mission cards

I need help on my mission cards , i am a new player in PB, and i dont know what is Enter in mission cards. Someone told me that i have to enter a game and finish it and it will be done since i have played 50games and i enter all different kind of mode and there the mission still didnt finish. Can some one tell me what the heck is this card about?

Ok go and try this for me me

Join a lobby that is for team death match and wait for the game to start, finish the whole game withouth leaving and it should work

Do no join a game that is already in progress