Whoops, you should have mentioned that in your OP, but I didn't pay attention to it either, so my bad. My reply was actually for NWN.
I haven't played NWN2 in quite a while, but when I check now I see that clicking on the spellbook options opens two windows, similar to NWN, "Known Spells" and "Memorized Spells". The memorized spell window should show headers for Level 0 and Level 1 in your case, and either empty or filled boxes below these headers (or, if not, click on the header to display them). If the boxes are empty, you just need to click on a Level 0 or Level 1 spell icon in the "Known Spells" window in order to memorize it. It should then appear in a box under the according level header in the "Memorized Spells" window. If the boxes in the "Memorized Spells" window are filled already, you can clear them by clicking on the icons under the level headers. Dragging icons does not work, it's only for puting them into quickslots, I guess.
At least this is how it works for me. If it doesn't work this way for you, there must be something wrong.