Board Thread:Oblivion/@comment-25424906-20140917211858/@comment-25508084-20141006201357

I'm a little confused by your question. You mean more Magicka or more magic spells? Magicka can be upgraded by leveling up, increasing your Intelligence and Willpower, as already stated by FacePalmKing.

Now, if you want different spells you'll have to buy them from Mage's Guild mages or priests, although the latter usually only sell spells that "benefit mankind", which means usually healing spells, waterbreathing and such.