To add a Word Document, PDF or other Media to a Post or Page use the Upload / Insert area.
Place the cursor in the text area where you want to insert the document.
Click the Upload Media Icon which looks like a small sun.
Upload the media from your computer. Once uploaded give it a name that you want people to see in the Title area. Experiment with other features in this window. You will get it with a little practice.
Click Insert into Post.
A hyperlink is created for your visitors to click and open your document. An example is below.