It is possible to add images within a Communication Template – it is slightly different than adding an image onto a Form or using an image using Image Library.
To place a logo or images within a template, this is done specifically using HTML code. Attached to this article is a training guide - ‘Adding Images to Communication Templates’ which should outline how this is possible.
Before adding images or logo's, contact your Communications/Marketing Team who may be able to assist you with this task. If not, the guidance is all included in the guide.