The most likely cause of this (i.e., you new "blank" documents are not blank, but have content in them from some previous document) is that you (or someone) inadvertently saved that content to your Normal template.
Keep in mind that when you ask Word for a new, blank document, it pulls a variety of settings from your Normal template. If there's content (text, graphics, etc.) in the Normal template, then you will get that stuff in your new "blank" documents, too. That can either be handy (for example, if you always want your documents to start with a footer showing your name), or it can be an annoyance (for example, if you get somebody's resume).
The quickest/easiest way to fix that is to simply Quit out of Word and then trash the Normal template. Then the next time you launch Word, it will re-create a new Normal template using the default settings - so any text that was in there (like your resume) will be gone. Keep in mind that any other customization that you may have made to your Normal template (for example, changing the default font) will also be lost, so you would have to re-define those settings afterwards.
What you're looking for is the Normal template, which is a file named "Normal.dotm". This file is located here:
Users / [UserName] / Library / Application Support / Microsoft / Office / User Templates / Normal.dotm
Trash that file and your new, "blank" documents should be blank once again.
Hope that helps.
