Showmanship and English Horse Tack Vocabulary

I do not know very much about showing horses, but I am interested in learning because my little sister who is eleven years my younger, recently started taking lessons. She is now beginning to take part in some competitions. I really want to support her because she really enjoys riding. The only problem is that I sit in the stands and have no idea what the judges, or anyone else, is looking at. She is in “showmanship” classes, and she has tried to show me the different English horse tack that she uses, but I can’t keep up with all of the names. I think I need to find a book for beginners to learn all of the vocabulary