There are lots of steps to set up questions and quizzes. I'd start reading these sections from the documentation:
https://docs.moodle.org/29/en/Quiz_module
https://docs.moodle.org/29/en/Questions
For Enrollments there are lots of options also. See https://docs.moodle.org/29/en/Enrolment_methods
For setting up the front page see https://docs.moodle.org/29/en/Front_page
For how the course listing works see https://docs.moodle.org/29/en/Course_list