The Moodle Dashboard shows thumbnail images for each course shown in the Course Overview block.  Here's how to set an image for your course.

course before   course after

  1. Go to your course's Moodle site. 
  2. Look for your Administration block, and choose Edit Settings.
    edit settings
  3. In the Description Section, look for the Course Image upload box. The easiest way to add an image is to drag and drop it from your computer into the upload box. 
    drag and drop to upload

  4. Click "Save" at the bottom of the screen. On the Dashboard screen, you should see your new image.
    course with image

 

To change the image, you'll first need to delete your existing image. Go back to Course Settings and click the image icon in the upload box.
click image icon

A pop-up box will have a delete option. Then you can upload your new image.

delete button