You can choose the courses you wish to insert in your Annual Personal Study Plan from the list of courses included in the suggested Curriculum. For compulsory courses you need to consider that some courses take precedence over the others. This means that, in order to insert certain courses in the APSP, it is necessary to insert the courses with precedence first.
Courses which take precedence over the others are listed in the Curriculum. Therefore, before you make your APSP, you should read the section related to your programme Curriculum in this Student Guide.

For Bachelor's degree programmes: before you can instert new courses belonging to the next academic years, you must have inserted in the APSP all the courses belonging to previous years, except for free credits.

In  any case, the system running the operations prevents you from defining an irregular APSP in which precedencies are not respected, since it will provide a warning message indicating which courses must be inserted before the others.