In order for your students to access your course, you must make it "active." To do this, click the Edit Course link in the Course Tools box on your course homepage (or on the far-right NavBar) and then click on Course Offering Information. On that page, click to place a checkmark in the IsActive box, next to "Course is active." Click Save and then click any link in the NavBar to return to your course site.
If your course is "active" and your students still can't see it, or if they are having trouble logging in to ICON, have them check the common problems and fixes in the online FAQ for Students.