After doing the registration you have to go through the enrollment into courses. You are either automatically enrolled OR you might encounter some obstacles. See the video which will help you to solve the problems.
0:28 - Enrollment period (check the time whether your faculty has opened the enrollment period).
1:00 - How to enroll in courses
1:11 - In the column "Enrolled" NO appears
1:22 - In the column "Enrolled" YES appears
1:28 - In the column "Enrolled" NOT POSSIBLE appears
1:36 - What means NOT POSSIBLE
1:48 - Apply for exception
2:39 - Seminar group enrollment
3:18 - Timetable