How to get more places for spells

[Zechnophobe]

Robert, the problem isn't that you have spells in your spell book, but rather spell scrolls. Spells you have learned do not take up 'space' against the number you see, only the scrolls. The solution then, is to either cast more of them, or sell them.

You can only sell scrolls at castles. Go into the castle, and open your spell book, you will now be able to sell scrolls by right clicking on them.

Good luck!