There are several ways that a learner can communicate with administrators and course contacts.
First, there is the in-app messaging feature. This can easily be accessed by clicking on the name at the top right, then selecting Messages.
From there as an Admin, you can view your inbox, as well as compose new messages to deliver to learners, courses, and groups. Learners will only be able to compose messages to users.
You can set a course contact email by navigating to your course, going to the General Settings tab, scrolling down to Email Notifications and Reminders, and entering it in the Course Contact Email section.
This email will be displayed in your learners' course portal.
Lastly, you can enable User Feedback.