While you can certainly insert an image into a Communications template (and you may also insert text to display just above or wrapped around the picture), there is no way to superimpose text so that it displays on top of (or in front of) an image.

If you need to add text to display over an image, then be sure to use photo editing software to create this desired look before adding the image to your template (so that you can update the actual JPEG image before inserting it into your template).