Before students can access your Moodle course you will need to make it visible to them. The options for this can be found by clicking the Edit Settings link in your Administration block.

There are two visibility options, either Show or Hide.

Select the option you want and then click the Save Changes button. Your course will become immediately visible or hidden from students, depending on the option you chose. 

In your course list, hidden course names and links will appear as grey, while visible courses will appear as red colored text links. Student will not see links to hidden courses.