Go to the course "About" page. Click on the gear icon in the top right corner of the cohort beside the name of the cohort to access the settings.
Select "Edit cohort description." Use the text editor to describe any special features included in this particular cohort. This is not a repeat of the course description, but a place to briefly say what is unique about this cohort, especially if you offer several cohort options. Save your changes and exit cohort settings.
See more detailed instructions and best practices under make a great course pitch.