[PHP] help with html through php

[Todd Alexander]

Hello all,
I am a complete newbie to php so apologies for what I'm sure is a
simple/dumb question.  I want to use php to include another html doc in
an existing set of documents.  In other words "123.html" will use php to
call on "abc.html" so I can make changes to abc.html and have it update
on all my pages.   
 
Again I realize this is a complete newbie question but I appreciate any
help you have.
 
Todd