Here are some resources to get you started designing book covers in MS Word. You can download a free package below with a guide and some book cover templates. If you want the Word templates to look like my samples, you need to check the font list and download the same fonts, or else look for alternates that are similar using the "fonts per genre" pdf.
I recommend you watch these videos first, and then download the sample package and read through the guide as well. Then play with the templates, add your own images and change the fonts to make your own unique book cover design.
How to make an ebook cover in Microsoft Word (1)
How to make an ebook cover in Microsoft Word (2)
How to make an ebook cover in Microsoft Word (3)
Here's another video I found on YouTube that is super helpful (and slower-paced.)
Here's a link to the sample package; you can use the Quickstart Guide or "Cheat Sheet" to troubleshoot and learn the ropes. There are a few fiction and non-fiction cover template samples to play with. The instructions are based on Word 2010.