You can add images to your course as items to be learnt. To do this, go to the 'Edit' page for your course, click 'Databases' and then select the database that you wish to add images to.
Please note: if your course only has one level, you'll have to add a new level to reveal the Databases tab. Alternatively, click on the 'Advanced' button at the right of the screen and click on 'Add column'.
Click 'Add Column' and select 'Images'; a new column will be created. You can add your images by clicking on Upload.
Please note: there is a difference between images added to a course by its creator and images added as mems by its learners. Images uploaded by the course creator will effectively be part of the course, and they can be tested on, whereas mems are optional, auxiliary tools that will not be tested on.