Question for those who have attended a concert.. please help?

okk soo iv never been to a concertt so i dont know how this works...im 16 and lets say its a no doubt paramore concert/no doubt with paramore......i really only whant to see one of these bands but ..how does it work outtt...when does it end if it starts at 7 ...and do they play equal songs or does oone band play more than the other..??if so wich one plays more