what is the difference between masz and mayą here?
It's "mają" :)
"Masz" is used with "you" while "mają" with "they" so it's:
what is the difference between ciastka and ciasteczka
"ciastka" is the basic word, and "ciasteczka" is the diminutive form which the course creators for some reasons decided to teach. It's more like a childish word or like "little cookies".
I am having trouble remembering the different genders. Does anyone have any suggestions that can help?