As you will see from the above examples, the German genitive usually follows the noun on which it depends - e.g. "die Wohnung des Arztes" (= the doctor's flat).
The only exception to this is that proper names and personal names in the genitive case usually come first. Unlike in English, there is no apostrophe before the genitive "-s" on personal names. Names ending in "-s", "-x" and "-z" usually add an apostrophe after the final letter of the name in the genitive case:
Grammar 7: The genitive of proper names
No apostrophes
das ist Marlenes Toaster
("that's Marlene's toaster")
links nebenan ist Marlenes Zimmer
("Marlene's room is next to it on the left")
Goethes Bücher
("Goethe's books")
Deutschlands Grenzen
("Germany's borders")
das ist Andreas Stereoanlage
("this is Andrea's stereo system")
BUT:
das ist Andreas' Stereoanlage
("this is Andreas's stereo system")
das ist Fritz' Schwester
("this is Fritz's sister")