To enable (or disable) Card View, you will first need to enter Edit Mode from your course outline. Instructions on how to do so are available here.
You can enable or disable Card View directly from the course outline. Click directly on the Card View button to do so:
If you choose to enable card view in a course with released lesson pages, you will be presented with the following warning:
Should you choose to proceed with enabling Card View in a released course, make sure that you are able to upload your new images quickly!
When you enable the feature, you will notice that a section to add images will appear within each lesson page. From there, you can directly upload your cardview images:
Any image that you upload will autosave.