I am writing a Research paper about the Swine flu and I have all the information I need but I can not figure out how to write the introduction.I...

In addition to starting broadly and narrowing down to your
thesis, another common way to begin an essay of the sort you describe is to start with
something opposite of what you're writing about, or, to rephrase and explain, to start
with something similar yet different.

In your case, you
could start with the traditional flu.  If you know the history, symptoms, and treatment
of traditional flue, you can start with them, then lead into the swine
flu.

Another option is to start with the common cold.  This
would be particularly relevant, since people seem to struggle with the ability, or
inability, to tell the difference.  This is vital because a cold doesn't usually require
a doctor's visit or hospitalization, while the swine flu
might. 

Starting with something similar yet different, can
be a way to naturally introduce your topic and thesis.