No, the boxes that are 'closed' are the ones that are 'transparent'. The boxes that are open have a stony texture. Try deleting one of Dak'kon's memorized spells (left-click on one of the spells on the left side)... you'll see the box is like a stone slot-thing.
So, spells available for memorizing are on the right, spells memorized and available for casting are on the left. This side also contains the spells that you've already cast (the grayed out ones) Left-click a spell available for memorizing and it will appear in one of the slots on the left side (if you have any available that is)
Do you know how to actually cast a spell? You right-click anywhere in the world and select Spells from there... took me some time to figure out... Also, when you're a mage, try reading Dak'kon's Unbroken Circle of Zerthimon. Depending on your stats, you can get some nice bonuses out of that...
