Do not blame the teacher: you'll get no sympathy from the many of us that are teachers and all of whom have students who moan that you're ineffective. I assure you we have equally strong opinions about you too. If you learn the definition of set, element and subset, then all of these questions are self explanatory.
Curly braces denote a set, what inside the curly braces are elements of that set. Thus {1} is a set that contains one element, that element is 1, whatever that may be.
Neither A nor B are subsets of C. A is an element of C. B is a (proper) subset of A
