How can i switch players

[Sliveron]

I started BB the last days and its really great. a bit lucky by the side but whatever.

My question is, i had a team with 12 players... and is it normal that the first 11 players are the players which play the match? And if not how can i switch them? or if someone is Injured replace him?
and yes... stupid question... but pls no stupid answers^^

[cardbourdbox]

You have to wait till half time you score or they score.