In Daylight, each image is assigned a random image that shows on "My Home" for all users who are enrolled or have pinned the course. You can the option to change this image to another in D2L's image library, or to upload an image of your choice for this. Additionally, you can set that course image as the banner on your course page.
If you prefer to see these instructions in a demonstration video, go to this link: Additional Options for Your Course
Click on the 3-dot menu button that appears when you scroll onto a course image in your My Courses widget on the home page. Click on "Change Image."
To choose an image from the D2L Library:
Type in your search term to see choices. Then, click on the "Use this image" button that displays when you hover your mouse on one of the results. The image will be changed.
To Upload an Image:
Click on the word "Upload" in the top right corner.
Choose where the image will come from. Navigate to the image or drag-n-drop it, then click "Add."
Click "Save" at the bottom of the Course Offering Information Screen. 
If you want to make the Course Image your Banner, Open "Course Offering Information" again. Then, check the box next to the image file.
Click "Save" at the bottom of the Course Offering Information Screen.
You can also always reach the Course Offering Information Page from inside your Course through the "Edit Course" link in the Navigation bar.