Good idea,observe how the assisted targetting works first before diving in.You will realise when you come round to trying it that its NOT as hard as people make it out to be.Whenever you are ready I could give you a basic rundown of manual attacking?
Its also good that you are mastering the other important things like plotting,how to intercept and put yourself and the target at the right place at a predefined time,thats just as rewarding because you can prepare for an attack you have already set up for say,12 hrs time when its dark.I'll never forget the first time I nailed a ship manually and in the spot I chose on the ship too,fantastic achievement.And,its just as disappointing to realise your torp passed harmlessly by its bow or stern,usually the speed setting is to blame here,vital you get the speed right!
How long HAVE you been playing S3 anyway? ( just curious)