-'s (the girl's name) and of... (the name of the book)

A- We normally use -'s for people or animals (the girl's... / the horse's... etc.):
the girl's name the horse's tail                      Mr. Evans's daughter
a woman's hat             the manager's office             Sarah's eyes

• Where is the manager's office? (not 'the office of the manager')

• What colour are Sarah's eyes? (not 'the eyes of Sarah')

Note that you can use without a following noun:

• This isn't my book. It's my brother's. (= my brother's book)

We do not always use -'s for people. For example, we would use of... in this sentence:

• What is the name of the man who lent us the money? ('the man who lent us the money' is too long to be followed by -'s)

Note that we say a woman's hat (= a hat for a woman), a boy's name (= a name for a boy), a bird's egg (= an egg laid by a bird) etc.

B- For things, ideas etc. we normally use of (...of the book / ...of the restaurant etc.):

the roof of the garage (not 'the garage's roof

the name of the book  

the owner of the restaurant

Sometimes you can use the structure noun + noun

the garage door          

the restaurant owner

We normally use of (not noun + noun ) with the beginning / end / top / bottom / front / back / middle / side etc. So we say:

the back of the car (not 'the car back')

the beginning of the month

C- You can usually use -'s or of... for an organisation (= a group of people). So you can say
the government's decision        or        the decision of the government         
the company's success              or       the success of the company              

It is also possible to use -'s for places. So you can say:
the city's new theatre      the world's population      Italy's largest city

After a singular noun we use -'s:

my sister's room (= her room - one sister)    

 Mr. Carter's house                
After a plural noun (sisters, friends etc.) we put ' (an apostrophe) after the s (s’):    

my sisters' room (= their room - two or more sisters)

the Carters' house (Mr. and Mrs. Carter)

If a plural noun does not end in -s (for example, men / women / children / people we use -'s:

the men's changing room      a children's book (= a book for children)

Note that you can use -'s after more than one noun:

Jack and Jill's wedding      Mr. and Mrs. Carter's house

You can also use -'s with time expressions (yesterday / next week etc.)

• Have you still got yesterday's newspaper?

• Next week's meeting has been cancelled.

In the same way, you can say today's... / tomorrow's... / this evening's... / Monday's... etc.

We also use -'s (or -s' with plural words) with periods of time:

• I’ve got a week's holiday starting on Monday.

• Jill has got three weeks' holiday.

• I live near the station- it’s only about ten minutes’ walk.

Compare this structure with a three-hour journey, a ten-minute walk’etc

Join the two (or three) nouns. Sometimes you have to use -'s or -s'; and sometimes you have to use...of