Click the settings icon in the top menu bar.
Click 'Settings' in the drop-down menu.
Click 'Course Reminder Emails' in the navigation menu on the left.
On the 'Course Reminders' page you can adjust how often course reminder emails are sent to your learners.
When you have finished adjusting the course reminder email settings, click 'Save'.
If you want to send one-off course reminder emails, read How do I send a course reminder email to an individual user?