You can not specifically insert a code fragment into the head using the
"insert HTML code fragment" feature. It will insert in relation to where you
place the code fragment box on the page. If you have a code snippet that is
supposed to be inserted into the head, just try it anywhere on the page.
Frequently it will work anyway. If the code you are trying to add has to be
in the head, then you would have to edit the page code directly, and this is
beyond the scope and intent of Publisher's web building capability. You
would produce the *.*htm files, open them in a code editor, even Notepad,
and make your edits that way.

DavidF