Please can you help me? I need to set the enrolment method for a specific course. How do I do this? I am very new to Moodle and would appreciate your help. Thank you.
This sounds like a question for the 'General problems' forum ( http://moodle.org/mod/forum/view.php?id=50 ) not for the developer forum.
You may also want to include the version of Moodle you are using, as the instructions will be very different for Moodle 1.9 and Moodle 2.x.
Agreeing with Davo about location for this question, but, here's an answer.
Course administration > users > enrolment methods > Add method drop down box
When you want to add users, click Enrolled users.
If you are using Moodle 2 then here is some information in the docs http://docs.moodle.org/22/en/Course_enrolment