Study Plan Tree Confusion

[Base]

So I'm trying to enroll in some subjects right now, but I have no idea where I'm supposed to put my subjects.



I kinda get the ones that just say "Level 1", but what do I put into the ones that I've highlighted?
When I click on the top two ones, it just comes up with the majors. Am I suppose to choose one or can I just leave those sections blank? 

[John President]

Science Level 1,2+3: As the name suggests, this slot on the study plan can be used for a Science subject of any level. I recommend that you leave it blank, until you run out of "Science Level 1" slots and you want to do another lvl 1 science subject.

Science Major: There are 4 slots here, for subjects in your major in 3rd year. These are all level 3 subjects.

Science + Breadth: You can leave these slots free for any level 2 or 3 subject you want - despite the fact that it isn't stated, these slots are only for level 2/3 subjects.

[Base]

Ah ok that clears things up. Thanks