In Spanish, you will never see an apostrophe "s." Possession is shown in a couple of different ways. One way is to use the preposition de (of) when you are expressing the possession in third person.
Example: el libro de Paco. = Paco's book
Another way to show possession is by using "possessive adjectives." Possessive adjectives are used to either establish a relationship between people or things, or to indicate that something belongs to someone.