In French, you can show belonging by using the word “de”, which means “of”. You say it’s the thing of somebody.
Marie’s house
the house of Marie
la maison de Marie
Pierre’s car
the car of Pierre
la voiture de Pierre
the children’s dog
the dog of the children
le chien des enfants
the school’s door
the door of the school
la porte de l’école
the man’s book
the book of the man
le livre de l’homme
Just remember that the word “de” contracts with some of the words for “the”:
de + le = du
de + la = de la
de + l’ = de l’
de + les = des