This question gets asked a lot. I do not believe there is a way to completely hide a course from a student but you can make it not obvious!
1. On your front page when not logged in settings, do not include any course listings.
2. On the front page when logged in settings, only include enrolled courses.
3. Remove the navigation block.
This will at least make it hard for them to see other courses but not impossible. As for the enrollment part, just remove all other enrollment settings for the course and only have manual enrollment enabled.