This script enables you to wait and automatically register for a course in Bilkent University's online course registration system. As I ( @alpernebbi ) have no access to the registration system as of 2016-02-02, this script is not tested and will not be developed further - at least not by me.
The current version of the script should work with up-to-date Firefox (42) and Greasemonkey (3.6). If you have both installed, click below and Greasemonkey should prompt you to install the script.
After installing, try to add a course or change a section as you would do without this script. When you come to the section selection step, the sections that previously would have been marked "Not Eligible" should be replaced with a "Wait" button. Click it, confirm your selection and the sections pane should start refreshing on its own. The script will look for the "Add" button for the section you chose, and will click it and confirm your registration automatically if it finds it.