This is a really broad question which off-hand would seem to take a lot of explaining to answer for someone unfamiliar with the printing process to competently grasp everything which takes place. It's not "rocket science" but it's not always easy for individuals to grasp right away either.
First.... Microsoft Word does not support CMYK color. Microsoft Word is not designed for commercial printing and has zero support for CMYK color. You just can't use Word if you need a CMYK file.
That being posted, Word can be saved as a PDF... and if you have Adobe Acrobat you may be able to covert the resulting PDF to CMYK color.
All this is very general and broad to help and explain things. Truth of the matter is, you may be best hiring someone who knows all this stuff to convert your file for you. It could be a simple matter for a knowledgable person while being far more confusing to someone with no experience and looking for a quality product, it's difficult to say for certain without seeing the files.
Additional information..... CMYK is not "for images". CMYK is for everything. A printing press holds 4 inks.. Cyan, Magenta, Yellow and Black... from those 4 inks millions of colors are created by printing the inks in small dots next to each other so the human eye sees a single color.
It doesn't matter if the color is applied to text, photos, illustrations, etc. If it's color, this is how the color is created in CMYK process printing.
It is customarily a bad idea to use color on small type. Small type is often best set as just black so it remains solid and readable.
If you have text set in a color, you need to ensure that color is built using a CMYK values. In other words 100%C, 0%M, 100%Y, and 0%K will make a green.... and so on. What specific percentages work in your case is entirely up to you.
In addition to the use standard colors, all images (photos AND illustrations) should also be in CMYK color mode. To edit an image's color mode you need image editing software such as Adobe Photoshop or The Gimp, etc.