All Moodle courses are created with the "Visible" setting on "Hide," so that the course will not appear on any course listings, except to teachers of the course and administrators.
(Experienced Moodle users may recall that this setting used to be called "Availability" and set to "This course is not available to students.")
To make your course site available to students, click the Course Settings link, which is in the pop-up menu under the Gear icon in the upper right corner of the course page.
In the Course Settings, go to Course Visibility (the fourth option down, under the Course Category, which will usually be your department and the current semester) and make the dropdown read “Show.”
Click “Save and display” at the bottom of the screen so the change takes effect.