All you need to do is log in to SkyPrep! If any of your users have a course deadline coming up and they haven't yet finished the course, there will be a section on your dashboard labelled Upcoming Deadlines. In this section, you can either click on the course name to go to the course's page, or click on the envelope button to send a message to those users.
If you click on the envelope button, you will see a screen that shows all of the users who have not yet completed the course.
Clicking on the Details button will take you to the course progress page for that user, where you can see what their exact course progress is, as well as make any changes to it that you deem necessary.
The Message All Users will automatically select every user in the list to be a recipient of the message you send. If you wish to only message select individuals, you can use the drop-down menu under To to select which learners you want to notify.
Simply fill in the Subject and Message, then hit Send, and your users will receive your message in their inbox.