There are different options available to enroll learners in your course depending on the type of course (Paid course, MOOC or Free course, and Private course) you have created:
However, if you have published your Private course and want to enroll more learners, you can click the Enroll New Learners link on the Course page (see Figure 1.2) and invite more learners through email.

Figure 1.2
However, if you want to invite more learners to join your Paid course after your course is published, you can click the Enroll New Learners link on your course page and get the course link for your course (see Figure 1.3). This link can be shared with your learners to enroll them in your course.

Figure 1.3
If you create a MOOC or Free course, you have all the course sharing options mentioned above, which are available when you create a Paid course. In addition to these options, you also have an option of directly enrolling learners in your course through email.