how to use a dotx file?

abrogard 
Oh dear, no one answered you. You probably have found out. But since 1839 people viewed this, let me try and quickly answer:

1. A template is a file from which Word instantiates a new document.
2. Templates appear in the Template area at the top of the File Backstage.
3. The Backstage is the non-document view you get when you click on the File Tab (Ribbon) in the Function Tab area at the top of your Word window.
   For example you'll find "Blank document" etc. as templates.
4. A template fil has the extension .dotx not .docx
   (to see that, in the File Explorer, go to Options, Click the View tab, then down the list, tick OFF "hide extensions for known file types"; press OK & start a new File Explorer window (Windows key+ E))
5. It reads like you are editing in the .dotx. Thus you are editing your template(!) but you still have no way to use it to instantiate new .docx files
6. To make the file appear in the File backstage, go to this folder in your File Explorer:
   C:\Users\user name\AppData\Roaming\Microsoft\Templates
   replace "user name" with your user name on your pc
7. Drop the .dotx file you received into this folder.
   Let's say your template is named xyz.dotx
8. Now, in Word in the Template area you should see xyz
9. If you click on that template, a new blank document, based on that template "xyz" is instantiated and shows in Word (you're back on the Home Ribbon / Function tab)

Hope that helps