I need help in properly citing page numbers in an essay in MLA format.For example, I am writing an essay on Guns, Germs, and Steel. It says I have...

There are two different situations you will encounter in
your writing.  In some cases, you are writing a paper with just one source, but in many
instances, you will be writing a paper with more than one
source.

In the case of the one source paper, the first time
you use your source, you must put the author's last name in parentheses, then the page
number.  Thereafter, just the page number in parentheses is
sufficient.

But when you have more than one source, you are
going to need to provide the author's last name and page number each time you use a
source.  You can see that otherwise a reader could be
confused.

In either case, you may also use the author's
name in a signal phrase, for example:

readability="6">

According to Smith, "Jackson's story has one
theme - Nazism" (23).

When
you use the author's name in this manner, you do not need to add it in the
parentheses.

Whether you need a Works Cited page is
something that should always have clarified with your teacher.