When completing the 12th Grade Courses section, under the field for Grade, you should select "Current Course" from the drop-down menu for classes you are taking during the first term of 12th grade.
For future classes that you will take before the end of 12th grade, select "Future Course" from the drop-down menu.
If you would like more tips on entering your courses, you can view the QuestTips section on entering your coursework.