Yes parenting classes would be good, what is your interaction with your daughter how do you react to the Tantrums? It could be that she is jealous of the Baby and she feels usurped when Baby gets all the attention, focus on her positive side and praise her when she does something good, get her doing outside activities and Games , get her Dad invilved and playing games with her.Set some bounderies and have time outs and keep to them, mostly she needs one to one attention, let Dad have Baby and you do things with her like you used to do.