In order to fins out what set each card is from, look for a small symbol at the bottom-left of every card.
See that little checkered box? It is something like that. Each set, or "expansion," has a unique symbol. You'll also notice that this particular card is numbered 54/114. This means that there are 114 different types of cards in this particular expansion. Arranging them numerically is another good way to organize your cards.
For a full list of expansion symbols and what they mean, look here.
If you have any further questions, feel free to ask!