
Local classes are often held in church halls and community centres. the vets notice board, or the Pet shop window will usually have one.
don't worry about being humiliated in class, as after all it is the naughty ones that need training!!!
contact the person running the class and inform them of your problem.
they may suggest you come to the last class which is usually for experienced handlers and their dogs who are training for compettion, your dogs behaviour will be less of an issue in this setting among more experienced owners, as long as you have controil over your dog. You may be asked to bring a muzzle.
The only way she will improve if she is trained around people and dogs, so that she learns they are not a threat. your own reactions will have a bearing here.
You should not try reasuring her, or shout at her, as if it is fear aggression both will heighten the fear response. You will need to be firm but matter of fact. Tell her no in a fimr voice. Keep your distance, but try to keep a loose lead, and check her back if she luinges, but praise when she is clam, and paying attention to you.
The head collar should be used to break her eye contact, as she won't be able to bark at them if she can't look at them.
If you find a trainer experinced in large guarding breeds all the better.