Now, when you preview a post, you'll see there's a new 'Attach' button at the bottom of the preview page.

Just click that, and select 'Word document' from the drop down list. It's important to select the right option from the drop down list of available filetypes. There's a filesize limit of 1MB, so let me know if you need that increasing.

Put in a short description of the file, hit the 'Browse' button, find the file on your machine and upload it.

Then hit the "Go back to display of content" link (which will return you to the preview screen) and publish in the usual way.
--
simon